Surging 86 VF500F

Hey Gang, After 6 months of other projects I finally got my VF500 running well enough to ride it. It starts right up and pulls pretty well but it has a bit of a surge when trying to maintain a consistent speed. I suspect it is a lean condition as it also runs a little hot. The set up is stock with the exception of shimmed needles and a K&N. The boots are also new and I don't think I have any vacuum leaks. I am going to try to adjust the fuel screws but I also wanted to look into going up a size on the pilot jets and perhaps the mains. It has the #38s in it now so where can I buy the #40s? I know I can buy a Dynojet kit but I really would rather not.
TIA,
Jim

 

Check carb synch. A worn-to-shit chain with a series of tight then loose spots can cause a surge too.

 

The carbs were only bench synced so yeah that is something I need to do. Do you mean the drive chain or the cam chain?

 

Camchain on the VF500 never fails. Massively overengineered. Pity you can't say the same about the valves and valve springs.

 

has anyone had experience with these kits?
http://carbjetkits.com/honda-vf500f-interceptor-1986-usa-non-california-ultimate.html

 

Not that this is related to any surge problem you are experiencing but..regarding a lean condition, are you running the right heat range sparkplug?

NGK DPR9EA-9

 

If you're willing to experiment a bit, i'd suggest opening out the idle mix screws about 1/4-1/2 turn to see if a slightly richer pilot circuit would help or possibly eliminate the problem.

 

I did check the fuel screws and three of the four were only 1 1/2 turns out. I opened them all up to 2 1/2. I took it for a short ride but it still seems to have the surge, A bit better perhaps but I think I need to do a freeway run to make sure. The darn thing is so quiet it is hard to tell.
I'll check the plugs too Heavy. Thanks

 

Get it up on centerstand and check condition of drive chain.

 

The spark plugs are NGK DPR9EA.

The drive chain looks great. It's a newer o-ring chain with no kinks I can see.

As soon as I get my replacement fan switch I'll take it for another run.

 

Seems like you may need another, better carb cleaning to fix the surging.

 

Perhaps. I've cleaned them a few times and replaced a couple of the f'd up carb bodies. The pilots are new but are the stock size (#38), You would not go to #40s?

 

OK. I have been able to put a few miles on it with the fan coming on like it should. It is better but still surging. I experimented with the choke and it seems to smooth out at about 1/2 choke. When I take the choke off it is very noticeable. It's also running hot. It still pulls pretty strong but idles a little rough without some choke.
So, it's lean. It could be dirty pilots or I need to go up a size. The fuel screws are out 2 1/2 turns so I am going to experiment with another 1/4 to 1/2 turn before I go with the larger pilots.

 

Update: I pulled the carbs again and cleaned out the pilots. They were plugged up. I put it all back together and it seemed to run much better. The surging was much improved and it started and ran great. After about 75 miles the surging started up again. I pulled the carbs and checked the pilots and a couple were plugged. I am running steel mesh visu-filters that are supposed to be good to 60 microns. Would paper be better? I also pulled the fuel screws and found one broken o-ring so I'll be replacing those. I pulled the petcock and the fuel screen is missing (naturally) and those are rare. Is there a suitable replacement? I think I have sediment in my tank so I may have that boiled out and coated. Not sure I want to put $100 in a dented (small dents) tank that is going to need paint.

 

As far as filters go....I've been running the little clear ones with what looks like a bronze colored stone in them. Not sure what micron they are or if they will catch sediment. Your talking about rust? Will anything catch rust powder? That stuff is fine. Looks like dust once its dried out.

I've read paper is the best but ethanol will kill them quickly. The paper melts....or the glue....or whatever but they wont hold up. I've tried them, they seem to melt and the sticky mess ends up in the carbs.

 

Yeah, I think that is my problem. The rust dust is clogging the pilots and God knows what else. It looks like I am taking the tank in for a treatment.

 

That's why, whenever i'm cleaning carbs for a VFRW member, i always ask them to drain and flush out their fuel tank befor refitting carbs.