Poor hot start

[SaffaChris]

Hey, I was out on the road the other day and had to stop to wait for a train to pass. I switched off my bike, and when I tried to start it a couple of minutes later it just turned over but wouldn't catch. Pushed it to the side, waited a couple of minutes, and then it fired up with a very slight hesitation.

It has no problem at all starting from cold, or if left for 5 minutes.

What causes a poor hot start? Too much fuel or not enough air?

Thanks!!
Chris

[SkinnE]

Generally speaking,

problems related to fuelling that get worse as the bike heats up suggest a too lean mixture (not enough fuel/too much air).

EDIT: I was wrong here. It should read "problems related to fuelling that get worse as the bike heats up suggest a too rich mixture (too much fuel/not enough air)." Sorry.


Without access to an exhaust gas analyser, you could do a plug chop to see how she's running. Google 'plug chop' for several how to's.


E

[whiskeypigeon]

i thought runs worse when hot = rich and runs better when hot = lean?

[Stevenjhow]

what you gotta do is hold the throttle wide open and hit the start button. As soon as it fires you wanna let off, you almost want to let off right before it fires....you'll get the feel for it after the first couple of times. My cruiser does it on hot days, like when I stop to refuel, it won't fire unless I do that. I think it's called vapor lock (fuel injection doesn't have this problem)

[SaffaChris]

Yeah, I also thought it was caused by too rich a mixture. Will definitely look at the plugs though! Meantime, I'll try the wide open throttle method.

Cheers!

[SkinnE]

Heh, yeah, sorry for the confusion. Too rich gets worse with more heat. Whoops.

[SaffaChris]

Ok, I didn't do a full plug chop, but I did take one plug out of each cylinder to have a look... definitely running too rich, the rear a bit more than the front.

Was thinking of installing a K&N airfilter, or pods (anyone heard of Conical Power? http://shop.wemoto.com/pictures.dyn?u=25327qqq3511569 )... maybe this will help? Might also put a few holes in the exhaust baffle to help the flow.

Chris

Front


Rear

[DefTrap]

Steady, do one thing at a time.
Pods - you'll need a jet kit.
K&N - don't see the point, they're quite expensive.

Personally, I'd buy a new paper filter, change the plugs, make sure the carb settings are spot on, check the choke cables aren't hung up, that sorta thing.

[whiskeypigeon]

Yup, definitely running rich there. Personally I prefer the pods because of their price, reusability, and it gets rid of that honkin airbox (makes tinkering with things a bit easier).

If you want to go the jetkit route, I have a used dynojet kit that's been sitting in my closet. Even comes with pre-drilled slides so you don't have to do them to yours (something you have to do with Dynojet and not with Factory). If your interested i'd say $75 shipped for the slides, needles, jets, etc.

You can get the pods from JD and if you can't get the baffle out of the stock exhaust let me know and I have an "alternate" solution to keeping the stock exhaust, but allowing more flow.

[SaffaChris]

Had a look at the filter on my bike at the moment... spotless, so I don't think it's clogged up. Filter looks the same as the HiFlo on wemoto.com ( http://shop.wemoto.com/pictures/bros/bros-hiflo.html ), does the OEM filter look any different?

Choke cable is fine... no problem there.

Might have to start messing with the carb mixture... eep! Not looking forward to that.

Whiskey, thanks for the offer, but mine's the 400, so the jetkit won't be much good. I'm curious about your "alternate" method of getting more flow through the stock exhaust...

Chris

[whiskeypigeon]

Had a look at the filter on my bike at the moment... spotless, so I don't think it's clogged up. Filter looks the same as the HiFlo on wemoto.com ( http://shop.wemoto.com/pictures/bros/bros-hiflo.html ), does the OEM filter look any different?

That looks identical to the OEM filter.

Are your carbs totally stock? Has anyone messed with the a/f screws? Although my only experience is with the 650's, I was always under the impression that settings from the factory were a bit on the lean side and if jets started getting clogged it would even leaner. Then again, I think when I got my Hawk after sitting in some garage for 2 years, the carbs were gunked and the bike was running lean lean, but the plugs looked like yours. How long have you had your Hawk?

Whiskey, thanks for the offer, but mine's the 400, so the jetkit won't be much good. I'm curious about your "alternate" method of getting more flow through the stock exhaust...

Well, I tried to pull the baffle out of my stock exhaust for hours. I drilled out the rivets and used a punch/hammer to try to rotate it around and get all the rust loose. I tried some WD, no help, and pretty much everything else in the book, no help. As I was giving up and about to button everything up, I was looking at the 4 holes where the rivets were and thought to myself, that allows more air flow. So I riveted those holes back up and drilled 4 new ones in the back plate, essentially getting the same effect as drilling out the baffle. I was planning on getting a new exhaust anyway, so I figured why not. I think they were 1/2" holes that I drilled and I can take a picture later if you want to see it. It worked for me and I know its kind of a ghetto method, but it doesn't look bad and has the same effect your looking for.

[SaffaChris]

Hey, no idea if my carbs are stock or not! Won't know unless I open them up. I've only had my bike for about a month, so I just want to get things up to scratch. The previous owner didn't know anything about bikes, but was religious on having it serviced regularly etc.

Maybe I should strip down the carbs and give them a clean. Any ideas on this?

Thanks for your help guys, much appreciated!

[SaffaChris]

All is well!

She's running MUCH better!

Cleaned jets with compressed air, made the mixture leaner, new plugs... problem gone!!

Carbs were all stock... 145 front, 138 rear.

Cheers for advice, much appreciated!

[NT696]

Stock jet size is 132 front / 138 rear I believe.

-Good to hear it is running better.

[SaffaChris]

Yep, but mine's the 400.