From what I read, TRX90’s have always been a lil cold blooded, and ours was no exception. Not that bad, just a little annoying, especially with the lack of elec. start. Lately however, it has gotten what I consider “Really Bad”. When its first started, and I can’t say cold because it was in the 90’s, It takes several (adult) pulls and I almost have to perfectly time my Pull with a little throttle punch to get it started. It sounds almost like it’s flooded. Once it’s started, and I rev the engine just enough to keep it running til it’s plenty warm, it runs just fine and purs like a kitten. In a nutshell: Cold it barely runs, Warm it runs and performs just fine (no hesitations and plenty of power). I’ve looked at all the posts about carbs and jetting, unfortunately, they all seem to start with “Warm the engine up to operating temp”. I’ll throw some ideas out, if anyone has run across some thing like this, help is always appreciated. I’m assuming its one of the following:
Carb adjustment - Where do I start? Could it be the float is out of adjustment?
Spark? I’ve put the ohmmeter to the Stator and it’s well within spec. Haven’t tried the coil, but I’ve always though they either worked or not (could be wrong).
Bad gas? I haven’t drained the tank… yet. The gas in it is straight from a station and I’ve added a little seafoam.

Next question, Who makes a Good Chain (428). When I was at the parts counter at the dealer where I bought the Thing, I mentioned that I was disappointed that it had been set up with so little chain adjustment left. This isn’t a quote, but the gist of his response was something like, The Chains on those things are Crap. I then asked him why the salesman hadn’t used that line when trying to sell it to me. The orig chain is a cheap O-ring with no master link. After I broke the chain break, I finally just took the sawzall to it and cut it off. For now, I just put a cheap CIC (ebay) one on, but would like to get a “good one” ASAP.

One last item; Any ideas on how to keep the Stator dry. My son has no fear of Water/Mud and he’s managed to “take on some water.” Since there is a pull start, I don’t believe its possible to make it completely water tight, so I’ve left the drain holes open. I’ve tried putting black tape around the pull chord opening and even went as far as adding a little air pump (minnow bubbler) to pump air into the Stator area with the hopes of creating a little positive pressure. Again, any ideas are appreciated.

Sorry for the long post.

 

The choke might not be working properly, or the mixture screw is out of adjustment, or there could be a small vacumn leak...any or all of these could be effecting the idle quality when cold, but leave it ok at warm. If all that checks good, then try the valve adjustments...if the intake valve is too tight, youll loose compression, and when cold, itll be hard to start.
Most of those small carbs have fixed floats and cant be adjusted, but if it were low float, itd have issue when warm too.
Im from mn too, and finding pure gas can be a real pain. Our pumps arent labeled for ethenol, but if it doesnt say pure gas, it has ethenol in it. The alcohol content will make the gas leaner, and on small motors (like this and lawn mowers and snow blowers) the ethenol content can make for too lean mixtures, and makes for hard starting. If its posible, only use pure gas in it.
Don seal up the drain holes, itll just trap the moisture in there, and then rust and corrorsion starts. Im not familiar enough about the motor, to help much on that. Maybe a service manual might help, there might be a missing gasket or something. If you dont have a service manual, the libraries might...check the 629.2 area of non fiction, and if your branch doesnt have any, ask the librian.
Check out dennis kirk for chains,theyre in rush city, and they have from cheap to excellant, but dont spend too much money on it, because a 90cc isnt gonna strain, even a cheap chain very much.
Welcome to the forums, and where in mn are you from?

 

Im not sure how much you want to spend, but I put a DID o-ring chain on my sons YZ80 and only adjusted it once. It was about $65.00 7 yrs ago but real tough.

 

Rocky Mtn ATV sells a good 428 oring chain. I think Its pretty inexpensive. They also have a few good non Oring chains that last and look for the ones like RK that are pre stretched we use them on some pretty powerful 2 stroke stroker 90s and have good luck. You might also look for an aftermarket chain tensioner.

 

Can't be much help here. The bike is just cold blooded, so I have learned to live with it. All my friends bikes are the same way too. I just warm it up carefully, then take it for a quick ride to be sure it is really warmed up before I let the kids at it.

As for the chain, my 90's must have a thousand miles on them, and the chains are original and in great shape. We don't wallow in the mud here in the desert (thank God), however.

 

First off, thanks to all for the great comments. Once again this forum is awesome.

Honda buster, I hadn’t even thought of the Valves, I’ll definitely check them. I’ll also swap out the gas as I’m sure it’s a ”Corn Blend” from the Kum&Go in WI. (I had to put the station name in here, cuz I think it’s the greatest name Ever for a gas station, though dawife doesn’t thinkso)
Mywifesquad & Fastestdad, thanks also for the comments on Chains. It’s always nice to have ref and some honest opinion b4 I buy. I bought a Chain tensioner, but haven’t figured out how to mount it yet without welding and changing the chain guard too much. The way my son rides, its gotta be protected well. Hopefully get it put on sooner or later. Looks like I’ll be checkin out DenisK for a DID or a RK. Here’s a tip, keep an eye on the clearance at the DK website, I’ve scored bigtime on tires, nerfs and a buncha stuff I didn’t even know I needed.
Buster, I’m from IGH (InnerTubeHts.). I used to ride MN, but thanks to the Mpls Star& Sickle, our combination of Enviro-***** & woosie legislators, and the confusion of what’s legal and what’s not, I now do most of my riding in WI. (despite all the yellow “G”s). Please don’t anyone get offended, this is more a comment on the state of our sport than a rip on MN or WI. (Godz country)

This whole keeping the Stator dry thing is really Annoying. Why is it that it seems the Minis (all of em) seem to have a problem and the full size don’t. Geeessh, I don’t even think twice about getting “over the seat” and have never had a problem with a wet stator.

I did come up with one thing, but haven’t tested it yet. As I mentioned earlier, I’ve tapped a small air source into the stator area. But with the two drain holes and the pull cord opening it didn’t do a whole lotta good. So I fashioned a small cone out of high density foam. I put it around the starter chord right under the grip with the hopes that it’ll seal that hole up better. If that doesn’t work, the only other thing I can think of is to seal the existing drain holes and tap a new one with a nipple on it. Did I mention my son Really likes mud….

Thanks again, sorry about the long post (again)…

Ooops thought of one more question, Whatz the dif between a 428 and 428HD (heavy duty I assume), and are the HDs worth the extra$$?

 

Filling the tank in wisc is the answer. The law over there, is better....the only pumps with ethenol is labeled, the pure gas isnt. Its way easier to find pure gas in wisc.
I think the difference in the chains, is the hd has links made from higher tensil strength steel.

 

Thanks again for the help.
In case anyone cares, it was the Valves that needed adjustment.
Starts easy and purrs just like new.
As far as the watertight, its been way to dry where we ride to test it much.
(maybe we'll get a little of Katrina by the weekend, so we'll have some good mud again) [img]i/expressions/face-icon-small-smile.gif[/img]