Runs well...dies at stops.

[Guest]

Got the first real run on the 750 tonight.

One slight problem. When warm she stalls at stops. Doesn't happen everytime but more than not. Fires right back up and runs smoothly.
She accelerates and runs like a scalded cat. Very happy about that.

Carbs were off and cleaned thoroughly about 6 weeks back. Didn't use rebuild kits or changed the o-rings and carbs have not been synched yet. Idles between 1200 to 1400 or so with a bit of "hunting" i.e. bounces up and down.

Any thoughts?

Appreciate the input.

Cheers all.
Spyug

[UncleMike]

I'm sure people are sick of seeing me say this, but check your valve clearances. If they're off, you've probably found your problem. If they aren't, you've got one less thing to consider in finding your problem.

Changing those o-rings and gaskets in your carbs can't hurt either. Get 'em from Robert Barr right here on the forum. It's cheap insurance for about $12.

~UM

[jimcor]

Check those clearances, but dump the recommended amount of SeaFoam or Berryman's B 12 Chemtool in the tank for a couple of tankfulls, both are just about the same formula, and they perform wonders.

[denydog]

Synchronizing the carb's has the most value for, and does wonders for a smooth and reliable idle. If the synch is way off, the bike can be trying to idle on 3 or less cylinders. You will also have to have the idle set too high, just to keep it running. The fact that you worked on the carb's makes it highly likely that the synchronization is off. The other sugestions have some value, but I would start with checking the synchronization first, myself.

Of course, the "hunting" could indicate an intake air leak as well.

[Billy Ricks]

Synchronizing the carb's has the most value for, and does wonders for a smooth and reliable idle. If the synch is way off, the bike will be trying to idle on 3 or less cylinders, and you will have to have the idle set too high, just to keep it running. The other sugestions have some value, but I would start with the synchronizing first, myself.

Valve clearance should be verified before bothering to synch. You are right that it is his most likely problem, but to do the job right the valves need to be run first.

[denydog]

Valve clearance should be verified before bothering to synch. You are right that it is his most likely problem, but to do the job right the valves need to be run first.

You are absolutely correct, and I agree completely that valve adjustment is basic, and needs to be correct. I just don't have any idea if he's adjusted his valves lately or not.

BTW- For me, a synchronization is about 10 times quicker and easier than adjusting the valves.

[spyug]

Thanks for all the input guys.

To answer the questions, I have not checked the valves.

I got the bike from a guy who had it in storage for 7 years. It has 19000km on it and the PO had advised and recorded valve check/ adjustment at 15000km. I figured that they wouldn't be out at that so I didn't check.

My feeling is the lack of carb synchro so I think I'll need to take it in to my regular wrench for that. He is busy as a one armed paper hanger so it is likely I't will be awhile before I can get that done. I think I will order the o ring kit and do that before it goes in for sorting anyway

I want to boot around on the bike for awhile to get it all loosened up again after its long sleep. Its a bit of a nuisance but I can cope with it for a short time anyway.

Thanks again fellas.
Cheers,
Spyug

[Billy Ricks]

If it's only been about 4,000 km the valves should still be okay. It's early in a motors life that they get out quickly. Concentrate on the synch.

[spyug]

Thanks Billy,
I nipped out for a quick ride to the bank and took the long way home. Still doing it but now when it dies and I restart it shoots up to 2000 rpm and kind of hangs there until I let the clutch out.

I'm kind of thinking I should buck up for a 4 tube manometer after all. It could be dangerous If I stall at a stop and the light changes and I don't get the fire relit before SUV soccer mum decides to peel out ( it nearly happened this ride but she just gave me the horn).

Thanks for the input.
Cheers,
spyug.

[Billy Ricks]

Have you checked for intake leaks? Try spraying a little WD-40 around the manifolds and see if the idle changes.

[spyug]

Going out to wrench in the man room after supper. I'll give it a whirl see what gives. I'm pretty sure I'm dealing with the out of synch situation but we'll look at all possibilities.

Thanks for the suggestions.

Cheers,
Spyug

[spyug]

I didn't get any wrenching done tonight...the urge to ride was too strong. I just went out for 10 mile jaunt but things are going down hill quickly so I'll need to get things sorted.

She's still dying at stops and now stumbling a bit on acceleration. I think I'm now getting crap in the carbs.

The interior of the tank is bad with surface rust and a baddly installed Kreem sealer. I got rid of a lot of rust with a vinegar rinse and I was intendening on watching it and cleaning and resealing it at the end of the season. It looks like I should do that sooner than later.

I really want to just ride but having had a small taste of the silky smooth power of this bike nothing less will be acceptable so its back to wrenching for now.

Cheers all,
Spyug

[txironhead]

Kreem is Krap. It works okay at first, but over time, especially if not used exactly right, it turns into goo that's nearly impossible to get out. Sounds like you could be clogging up the tank filter with all of that crud, possibly getting crud in the jets, too.

POR-15 makes an incredibly durable tank stripper/prep/liner kit especially for motorcycle tanks. Go to their website and there's a complete breakdown and instructions for the product. It also gets out old liner material. A lot of people here recommend phosphoric acid rinsed out with water and then rubbing alchohol with no liner. I was going to try that but can't find phosphoric acid anywhere, thank you EPA. Used to be sold as concrete etcher, now it's all organic stuff.

I'd use the POR-15 kit, and while it's doing its thing, tear the carbs apart and replace the o-rings and spray some carb cleaner and compressed air through them to get out the rust and Krap that's probably in there. And synching the carbs is easy, just make sure to get the correct (I believe 4mm) adapters. Your mechanic will probably charge more than the $40-50 the synchs cost, and then you can do it anytime you need.

[Billy Ricks]

trixonhead,

Go to Home Depot or Lowe's and pick up concrete etcher from the paint department. It's straight phosphoric acid. It's about $6 a quart and $13 a gallon. It's what I use.

[txironhead]

I went to Lowe's, Home Depot and the local "mom and pop" hardware stores and couldn't find any concrete etcher that was phosphoric acid. I even went to industrial supply shops and paint shops. No luck. It was all organic, EPA-friendly crap. The most concentrated dose of phosphoric acid I could find was OSPHO.