amain will have more GO-ENGINE stock shortly, "GO TECH" doesn't exist anymore :cool:
http://www.nitro-north.com/go-engine.html might be able to look after you ;)

how does the Gozilla handle in a buggy.. is it that much different from a MG66 or?? , had a chance to see one yesterday and she looks like a beauty.. mmm for the price.. cant help but grab one as a spare.. how does thy hadle :sneaky::tire:

3 x blown front bearings
 

Hi guys,

My motor isnt 10L old yet and Ive blown the oringal front bearing and 2 x ceramic. The third one didnt last 5 tanks!! Always get fuel around the back of the flywheel. It never really ran well after the first few litres.

Not sure what Im doing wrong. When both needles are flush the motor is rich and dies when accelerating. I raise the idle to get good idle but still rich, if I try to lean the bottom it doesnt run well.

The tune is never the same between tanks, Ive checked my fuel lines and tank, all is OK. Ive kept the clutch/shoes new all the time so I dont think its the clutch.

I went as far as screwing in the bottom end a few mm from flush, motor ran great until half tank, then had no punch, too lean as it was reving high when I came in. As I said, low end at flush or 3hrs from flush, it was too rich.

I did put a bit too much after run oil a few times, this may explain the leaking around the flywheel but the worn bearings??

Im going to shelf this motor but wanted your opinion. Reading this thread, dont think many have had much trouble??

Thanks.

I've had great experiences with Go engines. And on both that I had, I barely had to touch the needles at all.. VERY minor adjustments on the LSN maybe.. Anyway, I'd buy another no question..

Your problem is all in the tuning of the bottom end and idle gap.
You say you raised the idle - this was probably the begining of your problems.

Read the post I have just put up on my local forum - The average woman tune. This will explain everything, and should set you on the right path.
It starts about 1/3 of the way down the page at -

http://rcracer.co.nz/Forum/viewtopic...4785&start=330

On the GX motors the top end should be about 2-3 hours in from flush and the bottom end about 1.5 turns in.

GXII motors (2 needle carb) the top end is the same, about 2-3 hours in from flush, and the bottom about 3/4 to 1 turn in from flush.

These are with the idle gap set correctly at around .5 - .7 mm.

I did try those settings but seemed rich, I guess I can revisit.

But will a bad tune cause the bearings to fail?

The front bearing was worn to the point where it was very rouch and the piston was getting stuck at the top of the sleeve and I was able to move the crank lef/right and had heaps of movement at the bottom on the rod (in the hole where it connects to the crank).

you haven't been stopping the engine by covering the pipe stinger have you ?
blow front bearing seal.

Were you pre warming the engine before start up or were you using a kick arse starter box and cranking it over cold ? wich would put extra strain on the front bearing and con rod bushing as symptoms you mentioned.

+1 Flanno. It sound like it might have had a bit of a short, sharp and cold run in.

It would be hard to know if the rod / crank pin wear came first, or it was caused by the stuffed bearing.
Either way it doesn't sound too healthy. The front bearings will weep if your running rich, or put heaps of after run in, but it sounds like a serious bearing failure (or two !!).

Check the wrist pin. See if there is any lateral movement of the pin in the seats on either side of the piston. If there is movement there, or ovaling of the wrist pin retaining holes, then I would suspect a very harsh run in has left some play in the wrist pin and big end, thus probably causing the bearing wear through excess play.

you haven't been stopping the engine by covering the pipe stinger have you ? - Yes. I didnt think this would be an issue. People stop the engine via the flywheel but I thought this was out of choice and there were pros/cons for each?? Should I be stopping it using the flywheel?

Were you pre warming the engine before start up or were you using a kick arse starter box and cranking it over cold ? Yes, cold start using the Kyosho MultiStarter 2 (I think that's what its called), with a lipo. I was using a heat gun for the initial break in plus for another 1L after that but then stopped.

Is the wrist pin the gudgeon pin?
seats on either side of the piston/retaining holes - is this the 2 x holes that the gudgeon/wrist pin sits in held in by the 2 x G-clips?
Whats the big end?
So see if the pin moves left/right in the piston head?

Just looking at the motor exploded view and trying to match up the parts!

I will check the motor tomorrow...

Sorry for the all the questions, Im just curious/wanting to know/learn why this is occurring, you never learn if things dont break!!

You should always continue to pre heat for start up, especialy when engine still shows signs of still having metal pinch at TDC and stops / locks there still acassionaly.

Hi RCNitro13 -

Yes, wrist pin = gudgeon pin

Retaining holes are as you have described

Big end = the larger of the two bushings on the con rod. The bushing that sits over the crank pin

You are looking for movement of the wrist pin within the retaining holes.
Push the con rod up and down into the piston and see if the gudgeon pin moves around. It should not have any sideways movement across the diameter of the holes it sits in.
If it does, this means the whole rod is moving during the stroke putting undue strain on the crank pin / bearings etc.

Is go-tech all but dead? I see amain is selling the new 5ports for 139.00

Hi Matt,

GO is still going strong.

A-Main is selling all the GO USA stock that they inherited when they took over the distribution. They are all 2 needle carbs, so they are ditching them cheap to clear out stock and get the newer 3 needle version in. You will see the prices come more back to normal when those hit the shelves.

GO have just upgraded the 3 needle carb with a nice hard anodised throttle slide system for smoother operation and better longevity.

They have also just released (only this morning) a new entry level 5 Port motor - the G5T.
This is a turbo head 5 Port engine (based on the GX Series 5 Port) with a slightly different crank and 2 needle carb.
It's aimed at new entrants into nitro off-road, and would also make a great practice motor or RTR replacement motor. Pricing will be excellent.
You may see these at A-Main some time in the future, I can't speak for them though.

How is it all going Matt ? Hope all is well in your world :)

thanks shane. Any one still running 2010-11 xrays? I want to sell everything I started going through this morning and find I am 1 screw set-axles,center drive shafts off of building a whole nother' 2010-11 hybred xray 808. Did not need spare parts for the car. That and I have 5-7? go engines and 2 mg-66's :eek:
I am going to post a team magic set-up station for 1/8th buggies. Says it's for kyosho-mugan. But works on any buggy.