zip r3i bogging issues. engine all stock

[na96ek]

i have a zip with about 5000 miles on it. all thats done to it is rollers, clutch springs and a torque spring. lately (in the last 1000) miles it will sputter real bad on takeoff then once it hits about4k rpms it smooths out and takes off. in the last week or so it has gotten so bad that it is undriveable. i have to floor it for about 90 seconds and it will just sputter slowly gaining revs and then again take off. everytime im at wot and keep it going its fine but if i slow down and try to reaccelerate, forget about it. i have changed out 3 plugs in the lastcouple weeks and it seems to help for only a short amount of time. im assuming its running rich but the question is why? i did a comp test and got 142psi. new is supposed to be 198 per the manual. it does seem slower then it was new but not drastically. might be time for a 70 kit. maybe my carb is just junk? ive dissassembled it and cleaned it throughly. i also took my cylinder off and checked for stuck rings or any problems and it all looked great to me.

[BWSman67]

What condition is the belt in? 5000 miles is about the service limit for the transmission belt and a worn belt can be mis-diagnosed as a engine/carb problem.

[X7rocks]

check your belt and try lighter weights.

[na96ek]

im running 3 gram dr pulley sliders which have worked nothing short of amazing since the day i put them im. im on my 3rf belt already the last one being put on less then 10 miles ago. i dont think youre quite grasping what im saying. with the rear wheel off the ground i can floor it and it wont rev. it takes about a minute and a half to two minutes for the engine to clear up and gain enough revs to run smoothly. im no noob to combustion engines just scoot engines but to me it seems way too rich at low rpm. could i have a cdi problem, or do those pretty much ruin the entire sparking operation once they fail? once it gets above roughly 3-4K it runs great. and if i stay going i have no issues its only when i let the engine fall below a certain rpm. im asking about things it could be such as vaccum, reeds, low compression,bad carbuerator, torn gaskets etc? before i rip it all apart myself im trying to get ideas from maybe someone who has experienced a similar issue and found a solution.

[X7rocks]

check your air box,
Check your torsion spring, it can be a list..

[na96ek]

malossi yellow torque spring installed ~200 miles ago which also was a nice addition and i can see exactly where it helped out. filter is clean no leaks.....? i still think your missing my question. it does this with the belt off, sitting on the kickstand under NO load, or while its together sitting at a stoplight. this is a spark/fuel/compression engine problem! will someone please tell me if a cdi, reed, leaking case gasket, low compression with a factory jet, or a faulty carbuerator could cause a motor to bog for a couple minutes until a certain rpm is reached.

[zeonsredcomet]

You could have an issue with the a/f screw not being tuned right and a too small or large pilot and or needle jet clip too low or high.

[bakaracer]

When was the last time you changed the spark plug?

[na96ek]

i just put in a new plug yesterday and it had the same symptoms. today i tried running it and it got so bad that it wont even clear up. its to the point where you have to floor it to even get it started and as soon as it does start it eventually dies. i played with the air(idle) screw and the other screw on top and i did notice changes but not drastic and the problem was still severe. i decided to take the motor out today because it had developed a very loud knocking sound that was so loud it overpowered the exhaust. i had a buddy of mine listen to it and after racking our brains over it came up with a siezed crank bearing. this may infact be my whole problem. after pulling the intake manifold off and looking at the crankshaft, the fan side is all rainbow colored with brown and black tint which seems to me like excessive heat from spining in a siezed bearing and the other side is just clean stainless steel. im going to dismantle the entire engine this weekend with pics. still dont know what im going to do if the crank is trashed... $$$$$$$........

[zeonsredcomet]

That sucks man, Why don't you bring it to me tyler? You live right near by me. I can help you with this.

Let me know I'll be PM'ing you with my phone number.

[na96ek]

i wish i could come hang out and work in it together, but i moved back to pa last weekend! im gonna try and open the case tonight or this weekend and ill let you know how it goes. im kinda stuck on what to do because if my crank is fried the motor is pretty much toast. i was thinking of swapping a 125 4 stroke into it but im trying to get a better idea of what all is involved. my only other option is to dump a grand into this to get it back up because if i need to put a crank in it im not going to put a stock one in it and if i buy the crank that can support a crazy build im just going to go all the way with it.

[zeonsredcomet]

Sounds good to me! So you moved....oh man i would have helped for a coffee or some beer!

Let me know what your proposed setup is? May i make some suggestions??

[na96ek]

im looking to go with a polini corsa top end with a 19mm carb, CF reeds, ported intake manifold, not sure what exhaust yet. but my main concern is a crankshaft. I have a feeling that my crankshaft is bent, i did have some harmonic vibrations that progressively got worse over time. what type of gains will i be looking at with a ful circle crank? i understand i will have the added strength and capability of higher revs but how much of a hp gain alone is in the crank? i'd assume theres some as the full circle takes up more room in the crankcase increasing compression... i was looking at the malossi crank on provo, where might i look for other options? is stroking to beyond 72cc's possible with the corsa or do i need a different cylinder to do that?

[na96ek]

any input man?