Thumper? Road Warrior? Old School? ..... SRX250

I just wanted to thank hdscarbro for providing me with a source for the discontinued airbox-to-carb boots I was looking for.

I'll post the link here since it looks like they buy up and stock NOS parts. It might help others trying to keep these rare bikes on the road.


http://216.168.60.165/speedandsportinc/index.tpl


Thanks again hdscarbro!


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I've been thinking about making new petcock gaskets (and other rubber parts) by casting them from urethane rubber. From what I've read urethane has good resistance to gasoline but is not very heat tolerant. I haven't been able to find any web descriptions where anyone else has tried this. WDYT?

Here's the material I was thinking of trying. There's a smooth-on distributor not too far from me, I'm going to try to swing by there later this week to see what they say.

Go for it, I'll take one of those petcock gaskets.

Oh, and a windscreen too.



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Update- I tried to order a set and they are out for good. They just had the one set left...

Sorry man.

One of my old ones is still in pretty good shape if you want it.



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Hey guys, I am at my wits end with this bike...I rebuilt the carb again, replaced the intake boots, rubber diaphragms, air filter, petcock. Still runs very poorly when cold and will only rev with the choke on when warm. The jets are all clear.

My only thought is maybe the previous owner messed with the timing? Any other thoughts maybe I am missing something?

Thanks!

Right after I got it, my SRX600 was doing a similar thing. I hadn't got all of the crud out of the idle jet. You should be able to see through the idle jet when it out of the carburetor. Mine took an overnight soak in carb cleaner to clean out.

Also the idle mixture screw should be out about 3.5 turns (maybe more).

I don't think there is any ignition timing to adjust. If the head has been off, perhaps the timing chain is off by a tooth. Can't say from first hand experience, but I've read of similar behavior from this.

The idle jet is brand new, so I should be good there. Maybe I have to soak the carb overnight anyway. The head has been opened before, the previous owner was a BMW mechanic and he said it "looked OK"....

My idle mixture screw is out 2.5 turns right now.

I had the idle mixture screw out at 2.5 turns and was having trouble getting the bike to start when warm without the enrichener. It would idle OK though. Last week, I got a short stubby screw driver and player with the mixture adjustment while the bike was running. Mine definitely started better with the screw further out.

The service manual should describe how to set/check the cam timing. If you don't access to the manual, let me know and I'll send you copies of the appropriate pages from mine.

tight exhaust valve will cause it to act lean on idle too. Check the valve spec if you have not done it already.

I soaked a couple of different samples of urethane rubber from Smooth-On in gasoline for several days. The gas softened and expanded the samples quiet a bit. So, I don't think this urethane can be used for petcock gaskets.

I made a petcock gasket from my SRX250 which seems to work well. With the fuel line removed from my carb, there was a steady dribble of gasoline with the old Yamaha gasket. No dribble with the new homemade gasket. Here's a photo and brief description of the new gasket.

The softer rubber seems to work well. If it proves to be too soft over time firmer rubber sheeting is available. Here's the material that I used.

If you'd like to try one of these gaskets, contact me by private message.

Hey guys I rebuilt the carb again wi a new float. I put the bike back together with the mixture screw 5 turns out. Now it's runs better, not great, takes awhile to warm up. Will finally run with the choke off, just with a stumble right off idle. If you open the throttle too fast the bike still die out. It a.is at least rideable now

Update: After riding it around for 20 minutes, it does still run erratically. Once it warms up, the idle is not stable, it bogs right off idle, and the rpms drop slowly after reving. It also runs hot I think, I have taken a pic of the spark plug after the ride:

My SRX600 developed the same revving behavior shortly before I dismantled it for an engine overhaul (valve guide seals, 1st oversize piston, rod, bearings, etc). I was planning to worry about it when the bike is together again if the overhaul didn't help (probably wishful thinking on my thought). Your post got me wondering about the revving problem again, so I did some searching and found this post which might explain it.

Mine still has those same symptoms but to a lesser degree. Takes for ever to warm up, won't take throttle until fully warm etc.

5 turns on mix screw? Seems like a lot? My mix screw seems to have little to no effect, I suspect that circuit might be clogged so I'm considering an ultrasonic cleaning. Something to consider....

Thanks guys. Yes, the pilot screw doesn't seem to have much effect past 2 or 3 turns. I blasted out all of the passages in the carb though, they all seemed clear... In any case, I am pretty sure I am going to drop it off at a shop and have them figure it out. Riding season is starting!

I've had good luck cleaning my carburetors with an overnight soak in Yamaha Carb Cleaner/Dip. Be warned, it will soften (ruin) any o-rings that are left in it overnight. It's truly uniquely nasty smelling stuff.

Hey guys, update I got the SRX back from the shop. They rebuilt the carbs (again) and set all of the adjustments. One thing I noticed is they set the secondary to open very late. The bike runs better and is actually ride-able. There is still a stumble off idle even after the bike is warmed up. I am not really sure what is causing this. But I am happy to finally be riding.

Good news Brooklyn ......... I think?

Sounds like the late opening on the secondary might be compensating for the real problem though? Did they do an ultrasonic cleaning on the carbs?

I'm assuming you mean they open late compared to spec, right?

Anyway, glad you're riding