C&B Posted June 21, 2009 Report Posted June 21, 2009 Thanks, I'm suspecting my crank seal too. This was all new from HJR last year, but still could be bad I guess. Stock bearings but straight cut gears. I solved the prob with bearing from NTZ. Heavy duty sob, well worth the money IMO . Havent had a problem yet. and i run straight cuts as well. Quote
gregrob Posted June 21, 2009 Author Report Posted June 21, 2009 QUOTE (C&B @ Jun 21 2009, 04:05 PM) <{POST_SNAPBACK}> I solved the prob with bearing from NTZ. Heavy duty sob, well worth the money IMO . Havent had a problem yet. and i run straight cuts as well. What problem were you having with the stock bearing? Quote
bonbon Posted June 21, 2009 Report Posted June 21, 2009 Hey I ordered some tie-rod ends so when I get them I will send you one. Quote
shanYE west Posted June 22, 2009 Report Posted June 22, 2009 Different bike dude. Loco wants me to blow up the fast engine. I'll say this nicely the first time. Please offer constructive input or don't post in my threads. :yelrotflmao: Sorry I blew up... no pun intended... Quote
mopar1rules Posted June 22, 2009 Report Posted June 22, 2009 It's on methanol. Don't get much higher octane than that. and yes you do add fuel when you add more timing. It's always best to go rich, then work your way down. This wasn't a jetting/timing combo issue as I stated in the opening post. The left cylinder is fine. Something happened on the right to cause it to go lean, start detonating and torch the piston. I just need to find out what. upping the jetting will keep the piston cooler during the hotter combusiton temps from the increased compression and increase timing....yes, but that's bandaiding it. if the fuel/air mixture is fine and its rich enough, its foolish IMO to being running it richer from increased timing or compression. anytime you increase the timing or compression, it will increase the combustion process, but will require higher octane fuel to help slow the combusiton process down enough and keep the piston crown cool enough, and to keep deto from occuring. also, sorry, but i didn't see/read fully in your first post that you are running methanol. i would deffinetly check crankcase mating surface for airleaks and cylinder base. also check the intake/reed area out for air leaks. you running a boost bottle? if so, check where they plug into the rubber intake boots, as they leak like a sivv there. just trying to help ya out man. Quote
gregrob Posted June 22, 2009 Author Report Posted June 22, 2009 No boost bottle but I do have the prodesign intake w crossover tube. I have always double checked that the clamps are tight but I'll look it over closley when I tear it down Quote
FireHead Posted June 22, 2009 Report Posted June 22, 2009 Did you get the head off to see what it looks like? I bet you have an air leak somewhere on that right cylinder. Word. :thumbsup: Quote
dajogejr Posted June 22, 2009 Report Posted June 22, 2009 The helical or straight cut gears have nothing to do with the deto on this motor. If it locked up solid from a bearing or crank failure...then I'd look that route. Fuel, be it gas or alky, cools the top of the piston. When you add more timing, you add more heat to the motor...so you add more fuel to compensate or cool the top of the piston. There is no exact science there, so you always start rich and work down. I'd like to know: Cranking PSI UCCR Dome cc Squish Thickness Squish band thickness Was it checked for an air leak or not? What kind of ignition, what kind of spark plug, what size gap. 4 to 8 degrees is a big step. Normally, that would rattle a plug loose in a 300 foot run if the motor didn't like it. I understand your hill/dune runs are much, much longer. My guess is it ran out of fuel...get pumper carbs, get a fuel pump...problem solved. For as long as you guys run, I don't know if bigger bowls will be enough. You still need to be able to get fuel into the bowls...and gravity can only do so much. Quote
2strokespirit Posted June 22, 2009 Report Posted June 22, 2009 Not always to say that a failed cdi will make both cylinders fail, it should yes, but one is always 1st to go.. I had this in the past on 2 customer's bikes.. This should be your last option.. Also your crank could have slip a little out of phase, but assume its welded.. Detonation tends to burn a hole in the piston due to pre ignition.. Most of the time lean mixtures burn the exh side of the piston which is the hottest side and melts firts due to a lean mixture.. If having a hole in the piston you have deto issues (most likely) 2 different things between detonation AND overheating due to lean mixture.. Quote
dajogejr Posted June 22, 2009 Report Posted June 22, 2009 Most of the time lean mixtures burn the exh side of the piston which is the hottest side and melts firts due to a lean mixture.. I would agree with everything you said except for this. On methanol bikes I've had mine break at the intake side, and have seen buddy's bikes break on the intake side from being leaned out. I got stupid with a power jet and went from 6 turns down to 2. Learned the hard way on that one. I keep that piston as a reminder to try and not be stupid. Quote
2strokespirit Posted June 22, 2009 Report Posted June 22, 2009 I would agree with everything you said except for this. On methanol bikes I've had mine break at the intake side, and have seen buddy's bikes break on the intake side from being leaned out. I got stupid with a power jet and went from 6 turns down to 2. Learned the hard way on that one. I keep that piston as a reminder to try and not be stupid. I agree with you.. That why I said "most likely". Its just a guideline and was most of the time accurate for me, although I had one where the whole head of the piston from middle to exh side was melted.. So thumbs up! Quote
gregrob Posted June 23, 2009 Author Report Posted June 23, 2009 The helical or straight cut gears have nothing to do with the deto on this motor. If it locked up solid from a bearing or crank failure...then I'd look that route. Fuel, be it gas or alky, cools the top of the piston. When you add more timing, you add more heat to the motor...so you add more fuel to compensate or cool the top of the piston. There is no exact science there, so you always start rich and work down. I'd like to know: Cranking PSI 155psi UCCR what is this? Dome cc 19cc Squish Thickness .045 Squish band thickness no idea, they're off the shelf 4mil 19cc gas doems from kevin. Was it checked for an air leak or not? Yes when the engine was assembled last year What kind of ignition, what kind of spark plug, what size gap. all stock ignition. plugs are BR9ES gapped at .018 4 to 8 degrees is a big step. Normally, that would rattle a plug loose in a 300 foot run if the motor didn't like it. I understand your hill/dune runs are much, much longer. I thought it would back the plugs out too if it didn't like it but they were both tight when it happened. Never gave any other signs of detonation My guess is it ran out of fuel...get pumper carbs, get a fuel pump...problem solved. For as long as you guys run, I don't know if bigger bowls will be enough. You still need to be able to get fuel into the bowls...and gravity can only do so much. I think you're right, and Kim at K&T agrees as well. I called him today about some billet bowls and I'll be sending him my carbs to let him go through them and set them up like he normally does for alky as well as put a set of billet bowls on with only one float. He says I may have to end up running a pump for as long as we stay in it out on the dunes. I think they may be ok setup correctly though with billet bowls. I ran the drag bike out at sand mountain with stock PJ's and no billet bowls and it never sucked dry. That was with a bigger main jet than the duner had as well, just that it was only in 4th gear pulling the face wheres the duner was in 6th at WOT when this happened. If Kim really doesn't think just the bowls will do the trick, I'll have him set them up for a pump. I ran a pump before but the carbs weren't setup for it and it just FLOODED with fuel and it ran like crap on the low end. I didn't put in the effort to tune it and just took the pump off. Also talked to Kevin and he said he'd probably start out at +6 and see how it does when I get it put back together, depending on the squish, compression, etc. Thanks for the input daj. Quote
Onesickcrewcab Posted June 23, 2009 Report Posted June 23, 2009 How long were you riding it? Its possible the float got stuck up and starved the engine for fuel on that one side. I've seen it happen before. Quote
dajogejr Posted June 23, 2009 Report Posted June 23, 2009 UCCR is uncorrected compression ratio. Cranking PSI alone is not enough to setup a motor. Squish band is how thick the solder is smashed, from tip to where it's no longer smashed. Get a set of alky domes from Kevin.... Quote
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