gk71f poor idle when hot

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kit352
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gk71f poor idle when hot

Post by kit352 » Tue May 09, 2017 9:47 am

so I'm still trying to find the quirks with my newly acquired gk71f. One of my biggest gripes right now is when the temp get up near the hot side of the guage the idle starts getting poor and can stall out if the temp gets too high. when I take off I usually have a slight hesitation then everything is fine. if I drive long enough for the Temps to get lower in the guage then the idle will be fine as long as the bike doesn't get too hot again. it's mostly in slow London traffic that causes my issues. normal riding is fine.

moforockband
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Re: gk71f poor idle when hot

Post by moforockband » Tue May 09, 2017 12:18 pm

This could be down to a couple of issues. Firstly I'd check why your bike is getting so hot, it shouldn't be. It's only around 15C in the UK atm, and your bike should easily be able to regulate it's temperature, even without the fan. If the engine gets too hot, the air fuel mixture will become affected by the heat. It will be ok when the air/fuel mixture picks up speed as the temperature of the fuel air mix decreases. I would therefore be checking that the radiator is in good condition, and has at least 90% of the fins in good condition. If it hasn't that is where the problem lies. If the outside of the radiator is in good nick, but the fins are bad, go get it re-cored.
- Check the water pump is bled and working
- Check you have proper coolant mix in there
- Make sure you have the correct airbox inlet fitted, ie that the air intake is facing the coolest air it can, ie stock!

kit352
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Re: gk71f poor idle when hot

Post by kit352 » Wed May 10, 2017 9:48 am

I just topped off the coolant and haven't ridden it yet but it was lowish. not where I think it would cause a problem but that might be a cause.
It doesn't get crazy hot either. it runs in the second of the 3 segments of the gauge. it doesn't get to the hot one but it does get to the end of the one just before it. I'm not sure where the bike should be running to be honest.

moforockband
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Re: gk71f poor idle when hot

Post by moforockband » Wed May 10, 2017 4:50 pm

Watch a youtube video of a nice gk71b and see where the gauge runs when it's being used? You can buy cheap thermal guns now, but you should really check your rad for clogging or loads of damaged fins. It should not be above 85C, most gsxr'400's run considerably cooler than 85.
If the cooling system checks out fine, then you need to be looking more towards getting the carbs re-furbed. It could be simply that the mixture screw o rings are knackered, letting in air into the carb.

kit352
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Re: gk71f poor idle when hot

Post by kit352 » Thu May 11, 2017 9:32 am

you may be right on the cards. The cooling system looks OK to me. I will flush it anyway just to make sure.

while trying to figure out my cooling system I found a lot of little things the old owner hide and it had a fair amount. The carbs are in need of servicing for sure I would say. That's the least of the bikes problems I think. Lots of little buggered up items that are adding up. I may have to think about getting rid of it but I will keep working on it for now until the v5 comes in. then I will make a decision.

moforockband
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Re: gk71f poor idle when hot

Post by moforockband » Thu May 11, 2017 10:05 am

Once they're fixed up properly they are really reliable, and not to mention one of the most 'fun' bikes to blast around on.
I prefer my 60 hp 400 to my 180hp zx10r! I'd imagine the sit-up and beg riding style of the 71 is perfect for covering miles. My newer (!) 89 one kills my wrists after 40 miles, especially if the road is bumpy.
The carbs are easy to re-furbish yourself. Watch a youtube vid 1st. Take them apart gently, replace knackered old phillips screws with allen caps, and replace all the o rings in the kit. Kits available from lifetek, ebay and Suzuki! If you can find some other owners who have done it, you can probably buy the viton o rings online yourself if you know the sizes.

kit352
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Re: gk71f poor idle when hot

Post by kit352 » Fri May 12, 2017 9:12 am

all I can find is the lifetek kit. nothing else is popping up anywhere really. I will order the kit this weekend.
hopefully I won't need anything else for those carbs. I can't even find jets for them really. if I do keep the bike I will have to keep a look out for a spare set.

my fuel tap is leaking as well. is it a simple oring in there or should I start looking for a rebuild kit.

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Re: gk71f poor idle when hot

Post by moforockband » Fri May 12, 2017 6:27 pm

On the later bikes these is a viton o ring on the fuel knob assy, check there 1st.
You won't need to replace all the jets unless they chew up when pulling them out. Might be worth replacing the pilots, as the drilling is tiny. The EBC ones work well from ebay. I would replace the float bowl gaskets as they will be perished also.

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Re: gk71f poor idle when hot

Post by Variablevalves suck » Sat May 13, 2017 11:56 am

Yes check there is no air lock at the pump, if not bled properly air can trap down at the pump and no water flows.

kit352
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Re: gk71f poor idle when hot

Post by kit352 » Mon May 22, 2017 1:15 pm

well the cooling system looks to be in good shape as far as the liquid is concerned. water pump has been bled and the system appear to be healthy and cycling but I still am getting temp creep. I need to look into the fan as I'm not positive that is working properly either. I haven't hit the red h section yet so I don't know if the fan will come on when it does.
I'm going to look into the carbs next. I'm not really happy with the looks of them anyway.


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