gk71f poor idle when hot

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moforockband
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Re: gk71f poor idle when hot

Post by moforockband » Mon May 22, 2017 2:33 pm

I still think your rad is your likely culprit. This is what gets rid of the excessive heat.
You may need to check also that there is nothing more sinister like head gasket leaks increasing the water temp. The fan should only come on rarely, and usually only in heavy traffic/hot conditions.
I don't know on your bike, but some gsxr4's have a heatshield keeping the rad heat and header heat from the top of the engine. Check that also.

kit352
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Re: gk71f poor idle when hot

Post by kit352 » Tue May 23, 2017 10:54 am

I suspect it may be the radiator cap now. I rode it into central london today and i could here the coolant bubbling like crazy after i shut the bike down. Im not sure the system is pressurized now.

Now i just need to find a replacement cap. Im not sure if a newer 400 one will work or if i need an old one. If i can find a place nearby that can test caps that would be helpful.

moforockband
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Re: gk71f poor idle when hot

Post by moforockband » Tue May 23, 2017 8:15 pm

I've got a rad cap in a box of stuff here that is the same as this one http://www.ebay.co.uk/itm/Suzuki-GSXR40 ... xyYYlRpg55

kit352
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Re: gk71f poor idle when hot

Post by kit352 » Thu May 25, 2017 3:31 pm

I think thats the one but i cant recall off the top of my head. I need to find time to get the tank off and check. Problem is im riding the bike to work everyday this week.

Other than the heating issue it runs pretty good. Im going to start another thread with all its other little niggles and the fixes to help others out. Maybe in a couple weeks idk. Im pretty sure the carbs will be the first thing i go after next.

ventYl
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Re: gk71f poor idle when hot

Post by ventYl » Mon May 29, 2017 9:07 pm

Carbs are easy. Get yourself several cans of compressed air, can of carb cleaner, good sharp philips screwdriver, some flathead screwdrivers, set of 32 replacement allen screws (you will probably have to cut them shorter if you are not able to get them short enough), replacement O-rings and like 4 hours of time. If you are able to buy viton O-rings somewhere nearby then the only thing you really need from carb kits are float bowl gaskets. Unfortunarely I didn't write down O-ring sizes back when I was doing my refurbish. Hopefully some other member will have sizes written down or you can try to search for them online. Everything in these carbs is straightforward. Usually it is sufficient to strip carbs down, clean all jets and passages with compressed air and put it back together with new O-rings. If carbs were are dirty then some carb cleaner can be more handy than compressed air. Never use wires to clean jets. And don't overtighten pilot jet screw when putting it back together.

Be careful, there is a small O-ring under top cap and probably also rubber plug on pilot jet passage in float bowl (Bandits do have them, don't know about various gsxrs). If some of those will be missing you can get idle even worse than now despite new O-rings.

kit352
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Re: gk71f poor idle when hot

Post by kit352 » Mon May 29, 2017 9:44 pm

I had a go at working on the bike today and the po looks like he had already been at the carbs. I pulled them off just to look at them but noticed the bowl gaskets are leaky, it has no less than 4 different types of bolts holding the tops on and cylinders 1 and 2 are running very very rich. I think thats due to the airbox rubbers no longer sealing and one having a tear in it. I have zero idea how i will over come that situation with replacements impossible to get but i need to figure out things before i tackle that one. Pod filters would be my go to but that oval throat opening kills that idea.
I did get a good look at the fuel tap and its just a 14mm oring sealing everything and its in sad shape. I just gotta find a replacement at work hopefully.
I did check out my rad cap while i in there. The spring seems weak to me. Much easier to compress than my other 1.1 bar cap off a different bike. Shame they arent interchangable. Im not sure i want to risk buying a used one but new ones cant be sourced it looks like.
The bike is running pretty poorly now that i put it back together. Im sure pulling the carbs out messed something up. It hates to idle now unless its pretty warm and the choke is barely doing anything now. I did set the intake boots to seal better but they will never be great.

This bike is turning out to be quite a handful. I sense a valve adjustment in its future as well.

moforockband
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Re: gk71f poor idle when hot

Post by moforockband » Mon May 29, 2017 11:53 pm

The plugs can give rich readings because it simply isn't firing correctly.
You can use pods if you have oval carbs, you just stretch them on! On the gk73 bst's I use S+B filters 55mm, and they work OK. there;s a gk71 airbox on ebay atm.
I can send you a rad cap for nault. Just cover the post.
Viton only for the fuel tap remember.

kit352
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Re: gk71f poor idle when hot

Post by kit352 » Tue May 30, 2017 9:06 pm

I will take you up on that offer for the cap if you dont mind. Hopefully that takes care of my heating problem so i can work on other things.

Pm incoming.

kit352
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Re: gk71f poor idle when hot

Post by kit352 » Sun Jun 04, 2017 7:48 pm

I got the cap moforockband sent me. Its slightly different from a 71 but it does fit. The pressure ratings are the same but the mounting tabs are a little bigger. It goes on the same but initially putting it on is a little fiddly due to the position of the filler neck and the larger cap tabs need more careful alignment.
On a brief 20 minute ride i couldnt get the bike to overheat or boil over. My idle ability is piss poor after i took the bike apart last week so i couldnt let it sit and get hot on its own. I will try to get in a long ride this week sometime but now with the idle situation and my worries about it needing a valve adjustment i worried about traveling too far.

moforockband
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Re: gk71f poor idle when hot

Post by moforockband » Mon Jun 05, 2017 9:32 am

I did tell you to double check the cap, but it sounds as though it will do the job. You're gonna have to throw some money at the carbs. I wouldn't go on a long ride with them leaking/flooding etc. You may end up stranded with hydro-lock, or fuel pissing everywhere. Or throwing it in a hedge on fire etc.
It may be worth asking Mr variable valve his knowledge on the o rings, and try replacing the leaking bowl gaskets with OEM ones. Maybe the most cost effective way.
Last edited by moforockband on Mon Jun 05, 2017 7:00 pm, edited 1 time in total.


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