what are high miles for a boosted nytro motor ?
- Thread starter pylon
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Whatssss up Mikey????? Put Carillo rods and 3rd generation low comp JE Pistons in her (use the JE rings not stock ones), put in the aftermarkets head gasket that is now available (and head studs). Dump the hydraulic timing chain tensioner and put in a manual one, replace the timing chain AND the oil pump chain (they are about $30-$50 each up there I would guess). Port and polish the head. Do some aggressive timing (can't tell you about it on here, it's top secret) and your skippy. I would put in new valve springs while you have her apart. Just pull her out and take her to Chuck at Lakeside. With the motor work done you can run 17 lbs and it will feel like 20. Plus with the standalone you can run pump with a splash of 110 and never have to worry.
Besides the motor work you should replace the bearings on both sides of your drive shaft. I do mine every year. If you haven't done it yet replace your gear chain as well. Cheap insurance. I would also inspect the header and intercooler for tiny holes while your at it. Check your secondary clutch buttons for uneven wear.
Whatssss up Mikey????? Put Carillo rods and 3rd generation low comp JE Pistons in her (use the JE rings not stock ones), put in the aftermarkets head gasket that is now available (and head studs). Dump the hydraulic timing chain tensioner and put in a manual one, replace the timing chain AND the oil pump chain (they are about $30-$50 each up there I would guess). Port and polish the head. Do some aggressive timing (can't tell you about it on here, it's top secret) and your skippy. I would put in new valve springs while you have her apart. Just pull her out and take her to Chuck at Lakeside. With the motor work done you can run 17 lbs and it will feel like 20. Plus with the standalone you can run pump with a splash of 110 and never have to worry.
Besides the motor work you should replace the bearings on both sides of your drive shaft. I do mine every year. If you haven't done it yet replace your gear chain as well. Cheap insurance. I would also inspect the header and intercooler for tiny holes while your at it. Check your secondary clutch buttons for uneven wear.
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Whhhaaattss up Loui. Once he pulls the motor down to work on it the head will be off and timing done etc so it's the best time to put in the manual tensioner. The benefit to the manual tensioner is that you set the tension with the motor on the bench. At start up there is ZERO chance that you could skip a tooth. I have seen it 3 times and heard of it many other times happening with the stock hydraulic tensioner. The issue is with the TDC on the Nytro and where the cam lobes sit when the crank is at TDC. To be blunt, it is in a f**ked up position. Once you have the timing set with the crank at TDC, the timing chain on the intake cam sprocket, looks like it wants to come off (it is actually lifting up off the sprocket a little bit). I don't know this for sure but I think that is why Yamaha puts the timing chain guard stopper on the roof of the valve cover as a way to hold the chain down while the motor is started. I have done 5 of these my self and no matter what you do you cannot get that timing chain to sit tight over the sprockets. The hydraulic tensioner works by the oil running through it. That in itself is a problem. That crank is gonna be spinning over multiple times before oil even gets to the tensioner to release it to tighten down all the way. The way the stock tensioner initially releases is by turning the crank over by hand. It will release and tighten but not all the way. You can actually have a buddy turn the crank over and you can put your ear up to the motor where the tensioner is and you can hear it releasing. Problem is that it does not fully release and tighten until the motor is started. You can avoid all these issues by just putting in the manual tensioner. Most of the time the stock one will work but when it doesn't it will cost you mega bucks to rebuild that motor. At a minimum your valves are toast, if it jappens at high rpms your head could be killed and worse yet your rod bearings go and you lose a case because your rod poked out the block. Cheap insurance boys.
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pylon
Well-known member
hey kevin ! thanks ill give some of those things some thought . I was hoping to keep the stock pistions and mabey go with the rods powderlite offers . has any one used thier rods ? or know any thing about them ? the oil and cam chain the oil and cam chain though ill change out forsure ! mabey get some head work done while its appart too 
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pylon
Well-known member
yeah after some thinking im going to go with the carrilo rods ,tried and tested ! what about the JE pistions ? ive heard of a few people having issues with them in the nytro . I ve done my drive shaft bearing evey year now and did the jack shaft last year for the first time , same with the chain . Your breaking chain did make for a great day at keystone though kevin ha ! Also any one running diffrent valve spring?
ha ha you funny guy. As far as the JE's go they have worked all the bugs out of them. They now have the 3rd generation pistons and matching ring set for them. The nice thing about running low comp pistons vs stock pistons with a head shim is the extra power produced. With low comp pistons the entire combustion chamber sits at and below the deck so the explosion is taking place entirely against the cylinder walls. With a head shim some power is lost because some of that chamber is comprised of the headshim which sits a little above the deck depending on the shim thickness. The other benefit is there is less mass for the crank to throw around so the hit off the bottom is much more noticable. That crank can turn over much quicker.
I did run RD valve springs but the installer put them in improperly eventually causing my engine damage. I did notice when I first had them put in that the power gain above 18lbs was incredible. The stockers just cannot keep up after 20 lbs. If Chuck builds your motor you won't have to run over 17-18lbs. I climbed the upper lake shoot and the messy shoot and flew out the top on 14 lbs this spring in a foot and a half of good snow. At 17lbs my sled feels like it used to on 20 lbs. I would not do the springs again. They also cost an *** load.
I did run RD valve springs but the installer put them in improperly eventually causing my engine damage. I did notice when I first had them put in that the power gain above 18lbs was incredible. The stockers just cannot keep up after 20 lbs. If Chuck builds your motor you won't have to run over 17-18lbs. I climbed the upper lake shoot and the messy shoot and flew out the top on 14 lbs this spring in a foot and a half of good snow. At 17lbs my sled feels like it used to on 20 lbs. I would not do the springs again. They also cost an *** load.
I have 10,000k on my orginal Nytro running from 14-16 and up to 19lb.....haven't run any race fuel through it for a year as I now run the 270 mcx kit on pump. It runs 17-19lbs without trouble @ 6,000'+. Its plenty fast for me. Leakdown was less than 4% last we checked a while ago. Now its a test mule.......no love on that one
I know I have over 40,000k of boosted 4 strokes in the mountains. Never a major failure to date.
Stock internals are for me from here on in......only ever had one set of low comp pistons on my original RX1. All others since have been totally stock
Happy boosting
RS
I know I have over 40,000k of boosted 4 strokes in the mountains. Never a major failure to date.
Stock internals are for me from here on in......only ever had one set of low comp pistons on my original RX1. All others since have been totally stock
Happy boosting
RS
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