Jetfever

Hi Guys, I have not posted for a while.

I let my '98 Superhawk sit for a few months (but WITH a batt minder) and she was hard to start, only running OK on one cylinder, the other one firing part time. Battery seems strong.

I was only able to keep her running with the choke pulled on, and when she warmed up she ran poorly: Popping on decel, 1 cylinder still not firing full time.

I suspect I need to clean the carbs. Your thoughts?

Can you please help with a link to the service manual? I did a search an could not find it.

I have the tank and airbox off, need some help getting the carbs off.

Thanks, Steve

Syclone

Pull your carbs. Loosten the screws for the rubber carb holders and pull. Remove the bottom bowls, clean liberally, re-install and report back. Probably got some gunk in there while sitting.

Syclone

Service Manual thread is here.

Jetfever

Thanks for the quick reply!!!

I did: "loosen the the screws for the rubber carb holders". AKA intake manifold? I guess I did not pull hard enough. Should I get a little penetrating oil in there (around the rubber intake manifold)? or just pull harder. I did not pull very hard since I did not know if there were other parts to remove.

I have been looking at Jetting threads, Mike. The bike is stock except for some custom/ loud/ free flowing muffler cans. These were made by a guy who builds for Muzzy and a few other brands, but they are "one off". Should I Re-Jet the carbs or put the stock cans back on? She normally "carburetes" well, if not just a little abrupt at low speeds off to on throttle transition.

Thanks again for the help, will report back when finished! :-)

cliby

just rock them back and forth (right to left actually) and they will loosen and come up. if its not hot use a hairdryer on the rubbers. WHen you put them back on just push down hard on both at same time.

when you take them apart its the jets and the low speed ciruits in particular. so remove the jets and clean them - hold them up to the light. make sure the tiny hole is round and clean - its very small and when gunked up can be hard or impossible to clean on the very small jets (like the narrow opening through the pilots. Good luck.

Jetfever

Lets see if I can post a photo of Kimi and her 'Hawk, so you can see the pipes:

Jetfever

BTW, How frikin cool is the petcock on the bottom of tank?!!! I was about to drain the fuel and make a mess. Just don't forget to open it up before bolting the fuel tank back in place, eh? :-)

Bill, what is your opinion on different Jets?

E.Marquez

the petcock is a great deal,,, right up until you forget to turn it back on before reinstalling the tank,, Or you put the vac line on the wrong nipple (there is a blanked off one,,,,)and fuel does not flow.

Many times gas sitting in the carb for a few months will form varnish in the pilot jets.. replacing them is the simple, fast solution. Cleaning them in a chemical solution worked most times.. They are soft brass,, cleaning them with mechanical means not recommended, as many times users damage them (yes it can done,, but more often they are damaged)

Jetfever

I was planning on using carb cleaner, and a single brass electric wire removed from a "bundle".

I did not know it was easy to damage jets. I had a similar problem with my 1980 Honda 150cc Scooter. It worked the first time, but it is hard to start again.

I wonder if I damaged the idle jet when I cleaned it.

Is there an obvious engine behavior when an idle jet is damaged?

Ryan Ayers or Factory for new jets?

cliby

agree with TXsuperchicken about mechanically cleaning them - easy to damage and if you do get a wire through there is still a bunch of crud stuck to the walls. If you have a stock airfilter and only slip-ons, personally I think stock jetting is fine. You get some backfire on decels but that sounds cool. If you wanted to tinker you could shim the needles a tiny bit and get a little better midrange response, but these bikes are pretty good as is.

what is worthwhile, if only to make getting carbs off/on (and that probably is the biggest reason to do it IMO), is removing the PAIR system - I think there is a sticky here on that job, or find Greg nemish's website and he has a procedure posted on doing that. Lot less hoses once gone and does remove that backfiring on decels

Jetfever

Got the Superhawk jets clean, the float bowls looked great, no brown stains, a very small bit of black sand? in the bottom of the bowls, one idle jet blocked a bit more than the other.
I sprayed brakcleen through, (no brass wire, I read they are very easy to damage) and now need to replace air filter and start her up. Cleaned the main jets but they looked pretty good, a bit of crud on the needles.

I will let you know how she runs when I am done.

Why the hell do the carbs have a "coolant bar" and lines, and an electric sensor on them? Of course I dripped some sticky green coolant on the engine b4 I could plug the lines. I thought you would want the carbs as cold as possible?

PAIR system is long gone.

cliby

find the link for checking the TPS while you have them off - pretty easy to do and supposedly often out of wack.

Jetfever

Put her back together started her up and she barely runs. Will only idle with choke full out and pops/backfires, quits as soon as I give it throttle. It is actually a little worse than before I cleaned the carbs. Is it possible plugs could be fouled or did I not get the jets cleaned properly? Remember she was running fine a few months ago, before she sat for a while.

cliby

first be sure you have the gas turned back on AND the vacum hose to the correct nozzle on the tank- its not the obvious looking one. if neither of those do it, then see what you screwed up

Jetfever

Bill, She is getting gas. I am sure I turned on the fuel, and she fires right up, but runs mostly on the front cylinder. I know this since the front header gets warm before the rear.

So most of the problem is the rear cylinder firing part time.

I pulled the rear spark plug, it was a little oily, the gap was less than .40 more than .38, 13,000 miles.

I am at a loss as to what to check next, possibly a bad plug wire (do these go bad)? or a stuck valve? (compression check)? She seems to "pump" lots of air out the exhaust, but with a 2 into 1 v 2 system it is hard to tell.

BTW did a search, and I looked in "technical." I could not find the TPS check section. IS this for fine tuning? I doubt TPS would change in to 4 months (parked) to make the bike run this bad.

Not sure what you mean by this: vacum hose to the correct nozzle on the tank- its not the obvious looking one

cliby

re: TPS - apparaently most come from the factory that way - helps smooth out lower throttle movements.

check the choke (enrichment) cables as they attach to the carbs. they are easy to misthread or have in the open position. and then check everything for vacuum leaks. the only other thing I have done before is messing up a rubber diaphragm on the slider cover and then you get a stuck slider - worth checking those things.

good luck

Jetfever

Thanks guys, I finally found time to pull the carbs again, this time using carb cleaner in a spray can and she runs great.

Thanks for all the suggestions, help.

I started a new thread, more or less the same, but someone here asked me to post when I got her up and running again.

https://www.superhawkforum.com/forum...d=1#post239813

BTW, why do you need the fuel shutoff on the petcock? The bad/ old fuel would not drain without a little vacuum applied anyway?

8541Hawk

Well you need the manual valve in case the diaphragm in the vacuum petcock starts to leak.

Also the coolant lines to the carbs are a good thing. You can start a major discussion on that topic here but I have run mine both way and the improved atomization produced by heating the carbs is well worht it. Greg also has dyno charts the show you make more power with them installed.....but as always YMMV