View Full Version : Many Questions about Many Issues
Okay so here's the scenario. We sent my KVP out to Jim Perry at CKT Racing to be completely rebuilt over the winter and also to get a new header and 4 pipe for the senior class. When we went back to pick it up, Jim said that he'd done a full rebuild of the motor and carb (Which is what we asked for), but that he also changed the timing of the motor. We figured meh, why not. With all of this guys championship winning motors it's deffinitely gotta run strong now. So, we threw it on the kart, put everything back together and went out for a break in session at MRP. (My dad was driving though seeing as my hip was still broken) At MRP, my dad only got about 2 and a half sessions in before it started raining and we had to pack up. (He's too much of a pansy to run in the rain :rofl: ) After the break in day, we put the kart away for two weeks and finished up the Sr. Max and the DD2 for the season. So two weeks later we go to Norway for a practice day. I hop into the kart and give it about two to three warm up laps before I start to really push it. I knew something was wrong as soon as I hit turn 2 (The 1st hairpin) and the kart bogged down on me. I closed the low-speed needle down to about 1/2 turn to get the RPM's back up so I wouldn't stall, and then turned it back up 1 and 1/4 as I was nearing turn 4. The same thing also happened to me on the 2nd hairpin and I once again had to adjust the low-speed through the turn. Down the straight it wasn't performing either. I was only getting the kart up to about 12,400 RPM at most down and my foot was fully planted on the gas. I know that's a problem seeing as I was pulling over 14,000 with a 3-pipe. I tried playing with and taking apart the carb, changing sprocket sizes and adjusting the high-speed needle but nothing helped. The motor just wouldn't perform. On my third session out, down the straight right before the Monza, once I hit over 12,000 RPM's I literally felt the power drop out of the motor and start to slow despite the fact that I was down all the way on the gas. This happened for 3 or 4 consecutive laps so I decided to bring it in to avoid possibly sticking the motor. However, when I checked the temps., they were only at max 260 deg. F so I knew that I wasn't about to stick the motor. This only left me thinking that Jim's changing of the timing was to blame for my sudden loss of power. Before the rebuild, I was on a three pipe pulling high 48 second laps despite the 5 horsepower difference and reacing RPM's of over 14,000. Now, I couldn't do better than 53.42 with the 4 pipe running an 11-78gearing. However, when we called Jim, he said that all he'd done is rebuilt the motor and carb and that he did nothing to the timing. Both my dad AND I remember Jim telling us to our faces that he'd changed the timing of it. Well it looks like we're not sending any more motors to him any more now are we? I called Phil Gordon earlier today (seeing as we had bought the motor and kart from him) and he said that Brian Jacobsen from VKP was the guy who'd originally built and tuned the motor so hopefully he'll know what to do about the timing of the motor. Could it really be JUST a change of timing that'll make me lose 5 seconds off of my lap times despite the 5 hp gain? We're also having a little bit of trouble with the new Rotax Sr. motor that we put together. Last Saturday was the first time that we took it out only to find that it was completely lacking power. Out of four different drivers, I was the one who got the best lap time of 53.35 in it. I was able to drive the whole track with my foot planted on the gas and I know that I'm not supposed to be able to do that lol. We opened the carb to find that there was grease and dirt in there and that's probably why it was driving like crap but I just wanted to ask if there are any other possible factors that might've caused the lack of speed in the motor like jetting or carb tuning?
rystar
04-13-2010, 03:32 PM
Have you rebuilt the Carb? I know nothing about the timing on these things. Call Steve at Viking as he is the expert when it comes to KPV.
It sounds like it's super rich. But that is a total guess.
Different tuners sometimes have different carb settings. And usually when the blue print the engine, they blue print the carb as well. I'd ask CKT for their recommended needle settings.
Ryan: Yeah that's what I'm gonna have to do 'cause the motor was originally built by Steve so I'm gonna take it back to him. He did also rebuild the carb but I don't think that the carb could have any build-up after only 45 mins. to an hour of driving.
Rick: We didn't have the motor blueprinted just rebuilt. Also, we gave him a call from the track and he said to gear it higher and run leaner on the high speed. We did what he said but it didn't help at all. That's why I was trying gto adjust the carb myself while I was driving. Opening the low speed needle to 1 and 1/2 is what he recommended so that's what I did. It worked fine down the straght but when I even touched the brakes it started bogging down and nearly stalled if i didn't close it up then re-open it.
avmaviator
04-13-2010, 06:36 PM
I might recommend taking it back to CKT first... he might see something that he did wrong or forgot to put back (or something along those lines). It might be a quicker diagnostic then taking it to Viking and them going through the whole thing.... That's what I would do :) It is usual for a CKT motor to have these kind of problems... but you never know!
Thanks for the idea Arno but this is all up to my dad right now. In my opinion I'd take it back to CKT seeing as Jim's a really good guy and fairly easy to deal with but if we're putting up this kind of money then we're not really gonna have too high of a tolerance for little mistakes like that. Yeah I know people make mistakes but to screw something up this badly?! I was getting 48 second lap times on a 3 pipe! Now even with the horsepower gain I LOSE 5 WHOLE SECONDS?! It seems that a little mistake can go a LONG way!! So if Brian's dad can do a better job (which everybody says he can) he's gonna be our KPV builder from now on.
avmaviator
04-13-2010, 06:54 PM
Thanks for the idea Arno but this is all up to my dad right now. In my opinion I'd take it back to CKT seeing as Jim's a really good guy and fairly easy to deal with but if we're putting up this kind of money then we're not really gonna have too high of a tolerance for little mistakes like that. Yeah I know people make mistakes but to screw something up this badly?! I was getting 48 second lap times on a 3 pipe! Now even with the horsepower gain I LOSE 5 WHOLE SECONDS?! It seems that a little mistake can go a LONG way!! So if Brian's dad can do a better job (which everybody says he can) he's gonna be our KPV builder from now on.
Yeah I understand. There is no question that something is wrong. Hopefully you guys will find it soon :)
Well thanks for the optimism. Hopefully some of it rubs off onto us lol
I would wait until you talk to CKT about it. It might be something simple like a carb kit or wrong needle settings.
I would wait until you talk to CKT about it.
Rick, I'm not at all saying that I don't agree with what you're saying. I know that CKT makes very strong and fast motors but really that depends on how much money you lay down on the table. After talking to a few people about Jim and the reliability of CKT for an average local/regional racer like me, it didn't sound too good. From what some people who I will leave annonymous say, it seems that Jim is more in the business for the money instead of helping the average racer. Now I'm not saying that shop owners don't do it for the money because they obviously do. But local shops such as Viking do more to help out each driver INDIVIDUALLY. Jim builds high quality motors for high quality drivers with high quality checkbooks. It's because his work has such good history that he takes advantage of this. Am I saying that he's a bad guy? No not at all. But the thing is that I'm not gonna go out and spend thousands of dollars for a single motor rebuild and blueprint that WORSENS my lap times. Instead I'm going to get it done locally and get it done right. Will I have to pay a little more? Possibly, but at least I won't be getting the lower end of the deal. Like I said, we called Jim while at the track. The only advice he gave us was to keep the high speed needle at a half turn, the low speed needle at one and a half turns open and to start the kart with whatever the low speed needs to be opened at to start it (in my case between one half and three quarters open). When that didn't work, all that he did was tell us to go up a gear and close the low speed a quarter turn. After that he told us that we had to bring the motor in so he could take a look at it RIGHT after HE rebuilt it. Seemed kinda fishy to me so I decided to call Phil Gordon (Who I got the motor from), and ask who'd built the motor before we bought it and he said that it was Brian's dad. So I think we're just gonna end up sending it to him to check it out because it drove like a rocket before Jimmy got to it.
I totally understand how you feel. If you pay out good money, you expect good products/services.
All I am saying is that you should give them a chance to correct it. People make mistakes. And this might be one of those times. Or maybe it's just a simple misunderstanding. Either way, I don't personally favor one vendor over the other (CKT or VKP). I'm just saying you should give CKT the benefit of the doubt and first chance to correct the problem. Have you even spoken to them about this yet?
I would really be interested in hearing what another vendor has to say about your engine after they take a look. Especially if they confirm your suspicions. I hope you get it sorted out and get a good engine.
Well thanks for the sympathy Rick. I did call Jim when we were at Norway and he said to bring the motor back to him so that he could check it out. At this point though it's my dad's choice. Like I said, I trust that he builds good motors and yes I know that people make mistakes but still from all of the stories that I've heard over the last two days it seems as if my dad and I are getting steered in the opposite direction from Jim and CKT. I'll try to convince my dad to try and take it back to Jim but if Jim A) Charges an outrageous price to go through the motor and fix any problems -or- B) Goes through the motor but the problem persists, he's no longer going to have business from us.
avmaviator
04-14-2010, 08:26 AM
Well thanks for the sympathy Rick. I did call Jim when we were at Norway and he said to bring the motor back to him so that he could check it out. At this point though it's my dad's choice. Like I said, I trust that he builds good motors and yes I know that people make mistakes but still from all of the stories that I've heard over the last two days it seems as if my dad and I are getting steered in the opposite direction from Jim and CKT. I'll try to convince my dad to try and take it back to Jim but if Jim A) Charges an outrageous price to go through the motor and fix any problems -or- B) Goes through the motor but the problem persists, he's no longer going to have business from us.
Matt, I don't think Jim would charge you for going through a problematic motor that he built, but I could be wrong.
When you have problems with a vendor, it is very easy to get turned off right away from that vendor, especially if you hear stories left and right. For me personally, if I have a problem with a vendor, I usually try to see what they go to fix the situation (like Rick mentioned). If they fix the situation and all is good, then it can actually put more trust into that vendor. But if they don't, well just move on. Don't listen to all the stories out there because you will always find people with some kind of bad story (well, if there are nothing but bad stories/reviews that's another thing, I'm talking about the occasional miscontent story, especially from some members who know more then others ;) hah)
I'm just reinforcing what Rick is saying. If you go back to CKT and he doesn't find anything or charges you an arm or a leg, then you are done with them. But I would give them a chance (once again, I am not a CKT cheerleader, I have gone to all the shops in the Chicago area, I'm just a logical business advocate lol)
Arno, I'm not saying that I don't trust Jim. When we first bought the motor and kart package from Phil it was running like crap (This is when we were still TOTALLY new to outdoor karting btw). We took the motor and carb to Jim so that he could check it out and possibly find/fix the problem. As soon as we got into his workroom, he removed the bottom cover plate of the carb to reveal that about 60% of the little netting/screen (or whatever it's called) was covered covered with dirt. He removed it and then put the carb back together. He then removed the cylinder head to find that the piston was moving nearly a half millimeter in each direction. He then rehoned the cylinder and put in a new piston and rings. Just from this I was able to gain nearly 6 to 7 seconds per lap :D. So, we decided to trust him as our primary engine builder. We thought that just because he was able to do something so simple as replace a piston and rings and also help my lap time out so much that he must be to notch. Yeah maybe he made a mistake with the motor but almost every time we're there he HAS to mention the fact that he has over 200 national championship winning motors. If he always talks about it then why isn't he able to back it? I'll try to convince my dad to take the motor back to him this week but like I said I can't make any promises. If he does in fact charge US to fix his OWN mistake then we're done with him and CKT and it's as simple as that.
So what ever happened with this? Did you get it worked out?
LikeStig
04-26-2010, 05:04 PM
I just skimmed over this just now, and here's what I can tell. If the engine is only rev'ing to 12,000 rev's, it sounds like its too rich. If the timing was off it would be backfiring the whole way down the straight. If he only rebuilt it (Left the squish as VKP set it) it could be a problem with two different specs from two different builders; but I seriously doubt that. What seems more likely is that you are using the wrong length flex pipe. You may also (though I'm not sure if this is possible) having clutch problems.
I wouldn't doubt Jim's work for a second; but there are plenty of builders that I would never let touch my engines.
Hey guys sorry I haven't updated in a while. So my dad's final say was what ended up going down. We took the motor to VKP to have Brian's dad look over it and it turns out that the motor's timing was WAY off. Besides that, the carb needed a rebuild as well. He did both for us in two days. We then put the kart back together and ended up going out to Norway for open practice last Sunday in some unfavorable conditions. The track temp. was around 50 deg. with wind temp in the mid 40's. Also, it was my first time actually driving on the YKC compound so I had to get used to the handling of the kart in higher-speed turns. Unfortunately though, I only managed a fastest lap time of 50.62 seconds. The kart doesn't seem to struggle at higher RPMs as much anymore but I'm still having issues at both hairpins. After coming out of the forst hairpin and going into the horseshoe the kart still struggles to build up RPMs. It stays around the 7000 for about 3/4 of the "mini straight" leading into turn 4 and then it gets a sudden burst of power and shoots out into the turn once I hit exactly 10,000 RPMs. The same thing happens at the second hairpin coming out of the straight. We've tried various chassis set-ups and also needle positions but the times fastest time I pulled was with the high-speed needle opened at about 3/8 of a turn and the low-speed opened about 1 and 1/8 to 1 and 1/4 turns. I'm starting to feel that I just need to change my technique up a bit but I still don't know what exactly I might be doind wrong. How dou you take both hairpins Kyle? For the first one coming in off of the main straight I saty flat out on the gas through turn one and then take my foot off coming into the hairpin. For the one off of the straight I take my foot off the gas and just BARELY start coming in on the brakes at the start of the little "kink" going to the left. Still, upon entry I still have good speed and RPMs but then on the exit they just bog down and it takes a while to boulid them back up.
Thanks for the update! I'm glad you got it worked out.
Thanks Rick. Let's just hope I can fix any mistakes in my driving before the next race :redface:
LikeStig
04-28-2010, 03:20 PM
Hmm. Sounds too lean to me, but all carbs are different and the air density's always changing. Sounds like you are driving into the corners. As far as MY racing line (Which isn't perfect by any means) check the videos in my blog from Norway.
Yeah I am but I'm not hitting the rumble strips from the first 3 turns and i barely knick it at the second one. Plus, we tried running a richer mixture (1/2 turn on the high speed) on track but it would just bog down and had very little pull on the straight so I had to lean it out or else I'd stall.
Jeff Stamper
04-28-2010, 06:41 PM
open the needles to low speed - 2 turns and high speed - 1/4 turn and try it. Also, try another carb. Some are just junk
Thanks Jeff I'll keep that in mind. I don't think that the varb is junk though 'cause it was working really well for me last season. Might be worth a try though.
Jeff Stamper
04-28-2010, 11:21 PM
I have extras I can bring this weekend
I'd really appreciate that but it depends on which day you can come out. We might go out on Sunday for open practice if my dad's feeling better at all but I cant really make any promises at this point.
Actually, we're probably gonna have to go anyway 'cause Andy's finishing up our DD2 so I'm gonna have to go out and test it to see if the gear stays in or not so I CAN guarantee that we're gonna go this weekend but now it's just up to you and when you can make it.
JET Karting - Andy Finke
04-29-2010, 09:22 AM
Matt-
Like Jeff suggested, check out 2 or 2.5 turns on the low, and 1/8 to 1/4 turn on the high. That should help some.
Andy
Thanks for the tip Andy I'll make sure to try those out this weekend. The needle positions that gave me my fastest time (50.64 which is still horrible) were with the high speed a little bit past 1/4 turn and the low speed around 1 and 1/8 to 1 and 1/4. My dad also wants to bring out Phil Gordon (who taught me how to race) and have him try out the kart. If his time is faster by a half second or more then we know that we have to work on my technique. However, if the times are within a half-second then wer'e going to keep messing with the motor trying out different carbs and needle settings.
Jeff Stamper
04-29-2010, 09:10 PM
I run my fulcrum arm higher than most and I have to have my low speed at at least 1 7/8, so I am guessing that 1 1/8 is a bit lean.
Well it might have been the conditions we were running it at. The temperature was about 50 deg. on average and plus the carb was just rebuilt by VKP and hw changed the pop off so I need to get used to setting/adjusting it.
-UPDATE-
So last Sunday we went out to Norway for some more practice and to try and finally get the damn thing to work. As for carb adjustment, I was able to turn the high speed to a little bit over a quarter turn and kept the low speed open a little bit past two turns. Overall the motor was running a little bit stronger but it still isn't where it should be. We changed the gearing to 11/85 but I'm still not pulling more then 14,900 RPMs down the back straight. After reviewing my driving, both Phil and Dan said that my line is really good except for the horseshoe 'cause I'm overdriving turn two which I now more or less fixed. The gear change helped me keep enough RPMs through the slow turns to keep me from bogging down but still if I am to drop below 7000 Rs then I'm not going anywhere. We have a feeling that the timing might be set a little late 'cause I still feel like the motor is struggling for power on the straight which would also explain why the RPMs are so low. When I got up to weight I managed a time of about 50.4ish and when I was at 345 I was able to pull a 50.24. I know that these are still off from the average time but at least it's getting there. Also, the Rotax is acting up as well. We tried changing the jetting, clip position and entire clip on the original carb which did nothing. We then took the carb off from the DD2 but still it didnt help much. Alghough, when we changed the carb, the pick up on the stand did sound a little crisper but there was really no change in performance on track. We then took off the back cover to check the power valve and make sure it wasn't sticking. After taking it out, we found that there was a large carbon build up on the valve and that something was also causing the right side of the power valve to deteriorate. We cleaned off the carbon and took it out for a final session but it didn't help much. The power valve seems to be coming in really late (closer to 8000-9000 RPMs) when it really should be coming in at around 75-7600. I'm going to call TNR (where we bought the Rotax from) and see what Tim has to say about this.
Do you have an MyChron4 EBox or MyChron3 Gold? If you do, you can review the data from your sessions. It helps to find out where you are losing time.
We have the GPS system mounted on the KPV but we still gotta learn the damned thing. We went to the data acquisition course at MRP at the Wisconsin shop but it didn't go into much detail about how to actually USE Race Studio. We have the GPS mounted already and I've used race studio before but not with the GPS yet. The only issue we're having is that when we upload the data from the Mychron onto the data key and then try to upload it onto my laptop it doesn't go through.
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