Overheating with new big bore on KLX250
#11
10-25-2015 | 02:34 PM
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Possible point, the engine is likely not what is running hot enough to be a problem with your leg, otherwise your left leg should be getting it too. Did you put a pipe on the bike? I have a 650 and with no guard on the header, the heat is near unbearable without boots. I got it ceramic coated and now far less issue. The little stock guard will reflect some of the heat away, it's surprising the difference.
You should also make sure the coolant system is purged of any air. I believe that can cause over heating issues. The bigger bore may likely produce more heat, but consider when the fan is coming on. I don't remember ever having my 250 on, but I've not really thought about it or gotten in a situation where it would happen. On the 650 I have. The fan comes on in slow/go traffic where there is little movement. It also comes on when I get into some tougher trails where the same happens. Runs for a bit, then shuts off when all is good.
One consideration for cooling in general is the Thermo Bob that allows better coolant flow around the cylinder although it likely won't do a thing when at higher operating temps. It uses a bypass system like all auto engines have, allowing the pump to circulate coolant around the cylinder even when the thermostat is closed. Better more uniform cylinder temps.
You should also make sure the coolant system is purged of any air. I believe that can cause over heating issues. The bigger bore may likely produce more heat, but consider when the fan is coming on. I don't remember ever having my 250 on, but I've not really thought about it or gotten in a situation where it would happen. On the 650 I have. The fan comes on in slow/go traffic where there is little movement. It also comes on when I get into some tougher trails where the same happens. Runs for a bit, then shuts off when all is good.
One consideration for cooling in general is the Thermo Bob that allows better coolant flow around the cylinder although it likely won't do a thing when at higher operating temps. It uses a bypass system like all auto engines have, allowing the pump to circulate coolant around the cylinder even when the thermostat is closed. Better more uniform cylinder temps.
Thanks for the tips about cooling too. I had never heard of ceramic coating a heat shield. Sounds like a good move. And it is always hotter on the right of the engine - or maybe my right foot is more sensitive (?!) But now it is back to normal temps.
#12
10-26-2015 | 12:38 AM
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Joined: Aug 2009
Posts: 4,562
From: Delaware, Ohio
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I coated the entire pipe. You see it when you see a car or bike with a silver exhaust system. The ceramic keeps the heat in the pipe better, keeping exhaust velocity up - a good thing - and when it does that less heat is radiated off the exhaust to the outside. It is still hot, but not as bad. When my pipe was bare steel it radiated a lot of heat. It still does some, but not as bad. The big plus is no painting, no maintenance, no rust.
The most popular source in the US is JetHot, check their site out. You could research it there. Here it runs around $150 usd to have a pipe and muffler coated. If there is any sort of hot rod or tuner car scene in Thailand they may be sourcing it. Do a google search for ceramic exhaust coating Thailand to see if there is anyone doing it there. I have to think there would be somewhere close by in the Orient.
One other thing that can be done for less cost is to get some header wrap, it does a similar thing, insulating the pipe and holding in the head plus it probably easier to source for less cost, especially if you have to import it. Some riders have used it on the powerbomb type head pipes since it is easy to touch a leg against that bulge.
I don't know anything about the EFI stuff so I have nothing there.
The most popular source in the US is JetHot, check their site out. You could research it there. Here it runs around $150 usd to have a pipe and muffler coated. If there is any sort of hot rod or tuner car scene in Thailand they may be sourcing it. Do a google search for ceramic exhaust coating Thailand to see if there is anyone doing it there. I have to think there would be somewhere close by in the Orient.
One other thing that can be done for less cost is to get some header wrap, it does a similar thing, insulating the pipe and holding in the head plus it probably easier to source for less cost, especially if you have to import it. Some riders have used it on the powerbomb type head pipes since it is easy to touch a leg against that bulge.
I don't know anything about the EFI stuff so I have nothing there.
Last edited by klx678; 10-26-2015 at 12:41 AM.
#13
10-26-2015 | 04:10 AM
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Joined: Aug 2011
Posts: 516
From: Phuket, Thailand
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I have turned to the pros here in Thailand. I met one of the mechanics at the local Kawasaki dealer when I was there for a tyre. He moonlights doing big bore conversions. He disconnected a sensor, so now the F1 light is red all the time - but it runs as before. Not too hot, and smooth acceleration. He will do a permanent fix on Tuesday. He recommended NOT to use the EJK. He said its ok, but he prefers a replacement ECU. Same cost.
Thanks for the tips about cooling too. I had never heard of ceramic coating a heat shield. Sounds like a good move. And it is always hotter on the right of the engine - or maybe my right foot is more sensitive (?!) But now it is back to normal temps.
Thanks for the tips about cooling too. I had never heard of ceramic coating a heat shield. Sounds like a good move. And it is always hotter on the right of the engine - or maybe my right foot is more sensitive (?!) But now it is back to normal temps.
Sometimes it's best not to believe what Thai mechanics say & him not recommending the EJK is a prime example. If he has a trade account with APi he will get a decent commission supplying you with a ecu btw, Thailand is built on commission! I have two friends that have great running big bore bikes & Graham Gower on this forum runs a EJK unit with no complaints. They have full customer care backup from Dobeck performance (EJK) with upgrades, friendly advice in English by phone or email & instructions in English etc etc. You can adjust it yourself as it's simple to use & not be reliant on APi in Bangkok or a local mechanic.
Just food for thought the decision is "up to you" as they say in Thailand.
A very knowledgeable guy to talk to is Ian Bungy at Chiang Mai X-Centre - Extreme Activities
#14
11-25-2015 | 12:43 AM
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I talked to the guys in the local Kawasaki shop here in Chiang Mai. They recommended the ECU from API. I looked at the EJK Joel suggested, but decided to go for the simplicity of a straight ECU swap. Same price, and I can always use the mechanics her for tuning the ECU as they are not expensive.
So got the bike back - not overheating and running well - but - hard to start! Now been back to Kawasaki twice to get them to play with the ECU. Still no joy. The guy there who does the big bore kits for the shop said he doesn't know why. Never seen this before. So next step is to try another API mechanic who does big bore kits for Honda CRFs.
So got the bike back - not overheating and running well - but - hard to start! Now been back to Kawasaki twice to get them to play with the ECU. Still no joy. The guy there who does the big bore kits for the shop said he doesn't know why. Never seen this before. So next step is to try another API mechanic who does big bore kits for Honda CRFs.
#15
11-25-2015 | 01:59 PM
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Joined: Sep 2009
Posts: 5,050
From: Abilene, TX
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Some good possibilities and solutions have already been mentioned. One thing I was curious about. I've never even seen an FI KLX in person. Do they have the air injection system at the exhaust port like the carbed models? I know that richer jetting in a carb model can introduce greater heat into the head pipe, and that excess heat can definitely be felt on the right leg. Since the OP's bike doesn't sound like it's had any additional fuel introduced into the system by an aftermarket controller or injector, I'm pretty sure that isn't what's going on here. Do these FI models have an O2 bung in the head pipe or some other setup?
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