We were out testing last weedend, when the the motor started rolling over. Pyrometered the motor, too late! Seems the (plastic)oil pump drive gear failed, melted, boiled the oil and took the entire motor out.
Top end took the worst of it. Cam, rockers, bearings.
Heat signatures on wrist pin, and piston.
So leads me to believe, gear needs to be replaced with either upgaded material, billet, or higher volume pump system with external ports as well.
Have my kids racing up here in the high desert of So. Cal were its been around 85-95 degrees for the past month.
Yes, talked to Nathan (tech) yesterday, First he ever herd of problem. So far only replacement is entire oil pump system. He didnt mention anything about a upgraded replecement gear.
Like I said, motor is shot. I will be replacing it with another manufacturers model. But question is which?
Spent most of today searching around local race shops, and ebay.
There are replacements available "cheep". But I'll probally get what I pay for. Need some help here.
So far, what I've found out is....and take it for what its worth.
there are 125cc thru 140cc's with manual clutchs readily available every, some include either a 24mm or 26mm carb and all the electronics and wire harness needed to complete the swap.
Transmission gearing is a different story. Some give you the ratios, some dont have a clue. Some have the same shift pattern as the typhoon, N,1,2,3,4......some..1,N,2,3,4 (herd of problems with these).
Any good tech info, or personal experience with various engine sizes , and manufacturers would be great help.
Please no "opinions", just facts, thanks!
One of most important considerations is horsepower and gearing.
Looking for something close to the factory gearing as the motor that came out. As for horsepower: 14-16HP minimum.
I'm not sure if you did motor mods or not but I dyno'ed a stock 125 and it was @ 5.8rwhp 14-16 you are gonna need some major engine mods! and also the stocker with the clutch on the crank is not gonna hold that kind of power! Lifan has the clutch on the main shaft, high vol oil pump, big valve head, several after market parts. I live in Phoenix I have two stock engine sitting around.
Talked on phone yesterday to a performance shop in Arizona.
There offering a 140cc Lifan. Package comes with kicker & shifter lever, 24mm carb, manifold and filter, cdi box, coil, external oil cooler w/ braided lines.
Also says motor has big valve head, high volume oil pump, 5 plate clutch (manual type). claims: 10hp. Has plenty of aftermarket performance parts for this motor available in stock.
Machine shop and fabrication services.
Price: $400.00
Contact: pitbikepowersports@yahoo.com
Phone: 720-620-9200
Now thats the way to go!!! The motor will bolt up the only thing that is an issue is the stator/chain cover it is a little too long it hits the swing arm. You have to modify it. Get some port work, race cam, inner rotor kit, lighten oil sling, this bike will move!
Thanks for the tech info azextreme, made my decision alot easier! Got the chasis over at Noleen to be fitted with shocks for long travel suspension. Will be racing down at Elsinore on June 3rd.
This new bike may not be ready, but we'll still have another on the track there.
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