Need some help with an 86 TRX70.. This thing is killing me!!!

[Trackburger]

Okay, so I had been looking for a TRX70 for my daughter for a wh ile now, all of them seem to be beat to hell and the sellers want an arm and a leg. I was able to pick this one up a few hours away for a good deal. When I got it it started right up ran good but I didnt take it for a spin (fisrt mistake) Anyway it smoked then and I knew it needed a ring job but it was in such good shape I figured no big deal.
I purchased a whole new top end rebuild kit that included a new cylinder, piston, rings, gastkets etc. Stayed with the stock 70cc size. When I took it apart I marked the timingchain gear, chain and cam to make sure it went back together correctly. I did notice one of the valves was a little "burnt, but honestly cant remember if it was the exhaust or intake. So I start putting it back together and follow the manuals instructions to a "T", flywheel on TDC, (saw that the piston was actually there as well, but the timng chain marks I had marked were off by one tooth when I put it together. The "o" on the gear was aligned with the "v" in the head... I triple and quadruple checked everything, so I figured someone had been in there before and messed up the timing chain/gear placement... hence the burnt valve. Mind you the valve didnt look that bad. I'm only bringin this up to help "set the scene for what was and wasnt done, i dont think any of this is the issue at hand, but i could be wrong.

Okay... so I go to start it, starts on first pull idles great, revs fine in neutral, no more smoke, life is good!!........ but when i put it in gear and give it gas to go it bogs down and cuts out.

bought a rebuild kit for the carb....... same thing.

bought a new carb..... same thing....

any ideas???? If my daughter gets on it it seems to do okay, but I can tell it still wants to cut out especially if she really gives it some gas or go up any kind of incline. starting from a stop is a bit of a chore too. Now mind you she's 48lbs and I'm about 220, but this thing should still haul me around with no problem. right?!?!?!

So its really pi$$ing me of I cant figure this out.... put a new plug in... checked spark... nice fat blue flame.... just dont know what I'm missing. I have done lots of searches on this and seems like most people with the same problems were able to run theirs fine with the choke on, but not with it off..... if i put my choke on it cuts out as i would think it should.

like I said, right now it has new top end rebuild (not valves), new plug, new carb.... starts first pull with little effort, idles perfect, revs all the way up in neutral with no hesitation of sputtering, but when placed in gear and throttle applied to ride it bogs down and cuts out.

PLEASE HELP!!!! I just want to ride with my daughter!!!!! LOL:lol:
151690

[Blown 331]

Did you adjust the valves? Also do you have a good stock air filter in it?

[jb2wheels]

What's the fuel system look like? The tank on my 86 was complete crap - rusty, leaking, etc. How's the cap? Does it vent OK?
Basically, is it getting enough gas?
Since you changed the carb, I assume the petcock screens are clean.

How's the exhaust? No mud dobber nests or anything?

I wonder if the ignition is up to the task? Idling and revving free are low stress low pressure operations. Pulling a load puts a little more stress on the operation. Just guessing. Time to get out the OHM meter and see what the various coil/stators look like.

Self serving pics of mine marking it's spot...

151702 151701

[Blown 331]

Jb2wheels, Yours has a metal tank? Both of mine have clarke tanks but I thought vealmonkey said they had plastic tanks stock.

[jb2wheels]

Originals are metal as far as I know. Mine now has a "Wide Open" brand plastic tank - the white, generic looking one.

[Trackburger]

Mine has a plastic tank, everything is clean, I flushed it out when I got it to ensure there was no debris. The exhaust seems to flow fine, in great shape, no rust or holes etc...
It has a clean oiled stock filter, and i just spent $75 on a new OEM honda filter housing (the black canister thing)as the old one on it had cracks in the rubber boot that goes to the carb. Tank vent on cap flows fine....

I did not adjust or even check the valves for that matter..... will check those tomorrow.

[Blown 331]

If you have a slightly burnt valve it is probably recessing into the head and reducing clearance, the valve might be held open. I'd check that adjustment.

[bmanley]

I had a similar issue with my daughters ATC70. Bought a new stator kit, points, rebuilt the carb, and tried everything I could think of. I told a buddy of mine what it was doing and he said to replace the CDI box. Since my ATC didn't have a CDI, I replaced the coil and it has never run better. No bogging anymore and all kinds of power, and hauls my 200lbs around great.

[Trackburger]

Thanks guys, going to check the valve adjustment today hopefully, just ordered a new coil and plug wire..... keeping my fingers crossed!!! :)

[Blown 331]

Cool. Good luck!
Also jb2wheels, yours has an ATC motor in it. The TRX's have CDI ignition, thats a points motor in yours.

[jb2wheels]

I hope that fixes your issues - cheap, easy fixes are best.

<off topic> Oh I know mine's got a points engine. No CDI box or TRX kill switch either. It's an 82 engine. And the wiring is completely hacked. And the coil mount is a hack job to use the ATC coil. But, it ran great after I cleaned the carb and runs through the gears OK. I'll probably sell the engine - the TRX is getting a Lifan 125cc 3sp+rev from a donor POS ... I need to update my thread.

[Trackburger]

so I guess I should haave read the posts a little better, or at least looked at my quad, I ordered a coil and plug wire and turns out I guess I need the CDI box????? got it of Ebay... said it was dor an 86-87 trx70....??????? Guess I have to wait another week..... :(
left, what I have on the trx, right what I bought.....
151821

[Trackburger]

son of a b%$#@.... I see, so I have an ATC70 mengine in my TRX70........ Nice...... just ordered the RIGHT coil. I know your all probably thinking "what a tool" but this is my first 70 anything....lol

So... with that being said.... am i chasing the right gremlins still or could it be something else???? I would think the top end rebuild would be the same????? carb the same etc????? I feel like I wasted so much time for nothing!

[Blown 331]

The 1 on the right is a trx 70 coil. I see your 4 wheeler has the trx pull starter. But I'm wondering if you might have an atc engine with trx pull starter, side case and cage on it. If that would be the case, I think your point gap might be too narrow. Pull your cdi box and see if it's still starts.

[Blown 331]

We posted at the same time. See my above post. If it's not the valve adjustment, I'm thinking point gap for sure.

[Trackburger]

will check the gap when i get off work tmw. ordered the "right" Coil as well....... keeping fingers crossed. Thanks again!!!

[jb2wheels]

Another TRX with an ATC transplant? Interesting. So many more ATC70s were built I guess it's common?

[Blown 331]

Another TRX with an ATC transplant? Interesting. So many more ATC70s were built I guess it's common?

My second TRX70 has an ATC engine as well. I bought the bike for $200 because I thought my first one needed a CDI box (ended up being the nuetral safety switch). I went and looked at my second one and noticed the ATC pull starter. I told the guy it was an ATC engine but it did shift all up like a TRX (1985 ATC's shifted all up) and he pointed out the CDI box. Well I pulled the box off and it still ran. lol. I took it anyway. Can't complain too much for $200, and I got the CDI box I was looking for. It runs great, no smoke etc. It had nice ATC70 rear fenders and seat which is weird but I can always use that stuff. And the ATC pull starter is worth a bunch as well all know. I also robbed a few parts such as the front brake cables for my first one which is nicer and has an actual TRX engine in it still. Both of my TRX70s run and ride great.