86 Won't run without choke after diaphragms replaced

[WiVR]

This is my day to work on this bike. It is new to me, an 86 with 20,000 miles. When I picked it up, it wouldn't idle without choke, but ran pretty good on the road without choke.

 

I just replaced the 4 diaphrams and did the 2 ss washer mod on the needles. 1 of the diaphragms was completely seperated from the slide and all had a few holes.

 

Now the bike will not run without choke and if I rev it it wants to die. Will not stay running without choke and backfires a little while running. I have to adjust the idle with the choke. Seems like its running too lean. Trying to synch the carbs but can't get it to go without the choke. The indicators on the carbtune are moving but don't seem to be too high up on the gauge.

 

Any suggestions would be greatly appreciated.

 

Thanks

Kevin

[similost]

Just a thought.. something to check...

 

If the bike hasn't been running for quite a while, and there was any fuel left in the carbs, it could have evaporated and varnished. This will reduce the size of the jets from varnish build up. I would have cleaned them well while I was in there. For carbs that have been sitting a long time, I will find a torch tip cleaner wire that will fit in the jet and run it through a couple times with carb cleaner. I'll also make sure I spray the passages well.

 

OH.. you did check the float levels too right?

[nyjerry]

I just put the new diaphragms in and did the ss washer deal. I new something was not right when I had to use a lot more choke. I sync the carbs when it was warmed up and that helped. Bike would run ok when it was warmed up but I no longer had that zip that it had before and it was really cold blooded now. So I changed the ss washers out with the plastic pieces again. Another carb sync and the the bike runs good again. I have always gotten 45 mpg with the bike so I think I never needed that MOD anyways. Jerry

[WiVR]

I may try switching back tomorrow to the plastic spacers.

 

I pumped seafoam in through the fuel pump and am going to let it soak overnight.

 

Could it be the pilot jets and can they be accessed without removing the carbs from the bike?

 

I would prefer not to mess around with the air mixture screws if I can help it- they still have the plugs over them.

[Squeeze]

I may try switching back tomorrow to the plastic spacers.

 

I pumped seafoam in through the fuel pump and am going to let it soak overnight.

 

Could it be the pilot jets and can they be accessed without removing the carbs from the bike?

 

I would prefer not to mess around with the air mixture screws if I can help it- they still have the plugs over them.

 

You can't accesss the Fuel Jets without undoing the Carbs. And if you have teh Set laying on the Bench, you can only access teh Main Jets through the Plugs Holes.

 

But you need to tear down the Carbs and clean them up. If the Air Mixture Screws are still plugged, nobody was there for 25 Years....

[timgray]

It cold be so far out of sync from someone trying to sync it with bad diaphrams that when you put in the new ones it's wonky.

 

choke off can you rev it up to 2000 rpm or higher? if you can, sync at that speed and then let it down and see if it still runs. Mine was so far out that I actually was running on 3 cyl until I got the throttle nearly 1/4 the way open. You would be suprised at the number of bike mechanics that know nothing about carbs at all and will keep adjusting to compensate for ripped diaphrams.

[WiVR]

Getting closer. Cleaned Pilot jet 1 and 2 with a wire and some air. Put original spacers back on needles.

 

Was able to synch and set idle pretty close. Runs great under hard acceleration. I didnt do the mixture screws but am sure they could be cleaned too. I am going to continue with seafoam and see if that cleans it up.

 

Thanks for all the suggestions.

 

Now I have a heavy gas leak when the bike is running- will start a new thread.

[similost]

The fuel leak could be from a stuck float.. it is sounding like they may have been varnished up pretty good after hearing that cleaning the pilots helped... Varnish will make a float stick too.

[WiVR]

I was thinking that too but wouldn't the leak be coming from the front of the bike? The gas is streaming from near the upper rear shock mount and running down the front of the shock coil.

[Dano]

That's coming from the overflow tubes from the carbs, stuck float is the reason.

 

Dan

[similost]

Yep.. overflow tubes...

 

If it was my bike, I'd pull the carbs and pull them all apart and clean them VERY well...

 

I've always used Gunk carb dip for carbs that were varnished bad... You have to be careful with it though and make sure you have ALL rubber and plastic parts removed. This means any shaft seals too...

[WiVR]

Right on. It's the rear right. Any way to shake it loose without taking it apart (off the bike)?

 

Thanks

[similost]

Right on. It's the rear right. Any way to shake it loose without taking it apart (off the bike)?

 

Thanks

 

Yeah.. you might be able to.. but why risk other problems down the road? why not just pull all the carbs and do this right and not have any worries a 100 miles from home?

 

If there is a build up of varnish, later on a piece could break loose and plug a jet or passage..

[timgray]

Yep.. overflow tubes...

 

If it was my bike, I'd pull the carbs and pull them all apart and clean them VERY well...

 

I've always used Gunk carb dip for carbs that were varnished bad... You have to be careful with it though and make sure you have ALL rubber and plastic parts removed. This means any shaft seals too...

 

Cheater trick first. turn off gas, remove gas line and stick it in a can of seafoam. start and run bike until can is just empty and running bad. let it sit that way with the carbs full of 100% seafoam for 2 days or more. this will dissolve all the gunk in there. WE followed it up with an identical treatment of 100% techron and let it sit for 1 day. bike runs like new and when we finally took the bike apart for a different reason this winter I took off the carbs and opened up the bowls.. They were clean as new.

 

That solved it for a old bike a friend had that were varnished up bad.

[WiVR]

Going to try that. Going to drain the bowls and let the pump suck in seafoam then let it sit.

 

i've never used techron before.

 

Like to make the "cheater" method work before thinking about removing carbs.