High idle + popping

[whammst1100]

I have checked the forum for this problem but have not found the answer to my problem. My brother in law and I went through the carbs and cleaned them out(every thing was cleaned and rubbed down before re assembley) , re sync the carbs, new fuel filter, new air filter, new spark plugs gapped to 8mm, idle turned all the way out to where itis not even through the plate any more and it still idel at 2500rpm. The bike runs great. Enough to scare the crap out of me on the first ride.

This may be another hint. It is hard to restart after running. It will restart just not on the first try. Also the choke cable does freely move back and forth.

It does somevpopping on deceleration.

Thanks,

Will

 

[MrB]

Have you checked the timing? Belt could've skipped a tooth, is the popping coming from the exhaust?

 

[nhdiesel]

You have a big air leak somewhere. Check your vacuum hoses and Carb boots.

Sent from my LG-US670 using Tapatalk 2

 

[whammst1100]

thanks guys. I will check them this weekend.

 

[Ross Smith]

The popping can be from your PAIR injector control valves not closing due to a vaccuum leak when you decelerate. Air continues to be injected into the exhaust in that scenario. The bike "pop" backfires due to that injected air afterburning unburnt fuel vapour in the exhaust. Have a boo at those hose connections.

Ross

 

[ST1100Y]

+1 on the air leak...

 

[bdalameda]

I'd bet that the carbs are not seated properly on the rubber manifolds since you just rebuilt the carbs.

 

[Brant]

+1 what nhdiesel stated. If you didn't replsace those carb boots with new, likely where your vacuum leak is. IMO, should never remove the carbs without replacing the boots if they hadn't been replaced recently, specially at the age of these 1100's. Again, cheap insurance at $8 a pop, and beats doing the job twice.:banghead:

 

[whammst1100]

Dang it! I would have done that because we were all over those things. Do you have a prefered place to buy them. I have been getting parts from BikeBandit.

 

[Brant]

Dang it! I would have done that because we were all over those things. Do you have a prefered place to buy them. I have been getting parts from BikeBandit.

Just order them from your local Honda scoot dealer. There is certain parts replacement that are a bit critical to function AND lasting.......that's one of 'em...........as is OEM fuel filter. 82,000mi. on my scoot and it's never had a hiccup, just the vital fluid leak. BTW, aftermarket fuel filters HAVE given folks here issues, plus your fuel pump will be happier and last the distance if OEM fuel filter is used.

 

[whammst1100]

I did buy the oem filter for the bike. I will order the carb boots Monday.

 

[bdalameda]

The non-oem replacements made by K&L I think actually fit a bit better than the original OEM rubber manifolds and are much cheaper. I have been running a set now for a couple of years and they are still tight. Even when new, the OEM units barely tighten down enough as the clamps will bottom out. After aging a couple of years the clamps cannot tighten enough to seal well. The aftermarket manifolds seem to fit a little tighter and are slightly larger on the OD so the clamps can hold them tighter.

The rubber material on the aftermarket manifolds seems every bit as good as the oem originals.

Just my .02

Dan

 

[bdalameda]

Here is a set on Ebay of the aftermarket manifolds:

http://www.ebay.com/itm/HONDA-ST1100-INTAKE-CARB-HOLDERS-INSULATORS-INTAKE-MANIFOLDS-1991-2004-/380517103512?pt=Motorcycles_Parts_Accessories&hash=item5898963798&vxp=mtr

 

[Brant]

The non-oem replacements made by K&L I think actually fit a bit better than the original OEM rubber manifolds and are much cheaper. I have been running a set now for a couple of years and they are still tight. Even when new, the OEM units barely tighten down enough as the clamps will bottom out. After aging a couple of years the clamps cannot tighten enough to seal well. The aftermarket manifolds seem to fit a little tighter and are slightly larger on the OD so the clamps can hold them tighter.

The rubber material on the aftermarket manifolds seems every bit as good as the oem originals.

Just my .02

Dan

The original clamps, having the stops are there to keep from overtightening, causing a slight dimple where clamped , which could cause a vacuum leak, IMO. Understand that the aftermarket boots may be a bit thicker, but that may not necessarily be a good thing either. I am by no means an 'always use OEM' person, but like I previously stated, some critcal situations warrent it. Considering that any intake vacuum leak can eventually 'ventilate' a piston, and the fact that the original boots lasted some 20yrs.(92ST), and cost less than $40 for all four, I'll take my chances using OEM carb boots. Same would go for any of the pre-formed hoses under there. Many have cut to length and routed generic hoses under there, but again, not my choice as the hose material is NOT the same as OEM and IMO would not stand the test of time from the heat under there. The other deciding factor is Murphy'sLaw....if it can it will........somewhere 200 miles from nowhere.....

 

[bdalameda]

The factory manifolds are known to have leaking problems at times. The non-oem manifolds work well and seem to be a better fit. As to the vacuum hoses etc. I use a heavy wall silicone tube made for high heat and vacuum applications. The Honda hoses are OK but the hoses I use are of a higher quality and also cheaper as I buy the hose in rolls and use it on some of my other applications for turbocharger boost controls. The Honda Cooling system hoses are OK but there are better hoses available as well. When my OEM hoses began leaking due to aging and shrinking I replaced them.When theoem orings on the hose barb fittings underthe carbs began to seep I also found replacements made of superior materials as the original Honda orings that are known to fail. If you know materials and what type of materials are suited to a certain application, I see know reason to stay with the OEM hoses etc. Many OEM parts are not made out of the highest quality materials but made out of materials that are sufficient for the job at the lowest cost. Many times higher quality materials can be had at a lower cost than purchasing oem parts that have been marked up several times.

 

[Brant]

The factory manifolds are known to have leaking problems at times. The non-oem manifolds work well and seem to be a better fit. As to the vacuum hoses etc. I use a heavy wall silicone tube made for high heat and vacuum applications. The Honda hoses are OK but the hoses I use are of a higher quality and also cheaper as I buy the hose in rolls and use it on some of my other applications for turbocharger boost controls. The Honda Cooling system hoses are OK but there are better hoses available as well. When my OEM hoses began leaking due to aging and shrinking I replaced them.When theoem orings on the hose barb fittings underthe carbs began to seep I also found replacements made of superior materials as the original Honda orings that are known to fail. If you know materials and what type of materials are suited to a certain application, I see know reason to stay with the OEM hoses etc. Many OEM parts are not made out of the highest quality materials but made out of materials that are sufficient for the job at the lowest cost. Many times higher quality materials can be had at a lower cost than purchasing oem parts that have been marked up several times.

Very aware of the Super-Sil silicone hose, but being VERY flexible, had concerns of kinking in that tight of an area. Also very aware of O-ring color coding for different applications(fuel, high heat, antifreeze, etc.), and would be the only change from OEM if I had to do it again.

 

[whammst1100]

Finally got to install the new oem boots today. It did bring the idel down to around 1500 rpm. That is better than the 2,750 it was at.