Author Topic: CBR600 thermostat swap (Read 8150 times)

El Dopa · « **on:** May 25, 2007, 01:52:37 AM »

Has anyone swapped out the 400's thermostat for a CBR600 one?

Do you need to swap out the whole assembly - hoses and all, or can you just swap the thermostats over?

gsxr400 racer · « **Reply #1 on:** May 25, 2007, 02:38:46 AM »

thermostat

El Dopa · « **Reply #2 on:** May 25, 2007, 04:08:51 AM »

Quote from: "gsxr400 racer"

thermostat

I'll take that to mean you just need to swap the thermostats over and not the whole assembly, then.........

gsxr400 racer · « **Reply #3 on:** May 25, 2007, 06:48:00 AM »

yes sir

del la sol · « **Reply #4 on:** May 25, 2007, 10:07:48 AM »

Whats the advantage to running a CBR thermostat?

Red01 · « **Reply #5 on:** May 25, 2007, 12:22:39 PM »

I'm no B4 expert, but from reading past threads, let me see if I got it right.

Cheap and easy to find and opens at a lower temp.

del la sol · « **Reply #6 on:** May 25, 2007, 12:54:58 PM »

I've torn down the bike to repaint everything and do some modifications so I might as well replace it while I've got it apart, the coolant looked like it was original from 1991. I work in parts at a Honda dealers so my cost is $20, not bad.

Red01 · « **Reply #7 on:** May 25, 2007, 02:40:28 PM »

I thought there was a cheaper alternative using a Stant automotive equal that you just had to drill a steam hole in. These run $5-10 at your favorite discount auto parts joint.

El Dopa · « **Reply #8 on:** May 25, 2007, 04:45:41 PM »

Quote from: "del la sol"

Whats the advantage to running a CBR thermostat?

From the Factory Pro site:

"Part of the problem is, like ALL of the 93-95ish watercooled Suzuki's, that it's got a very low temperature coolant thermostat ~170f, or so. Makes them seem to run lean and not idle well when the fuel screws are set for best idle after a good ride. Install a higher temp thermostat from, perhaps a cbr600f3. We use ~190f thermostat, which is a bit higher than the f3, but 190f is where the engine runs the best and makes the best power. Either way, changing the thermostat is mandatory (trust me!). Then you can tune the carbs for best throttle response with the kit [edit: factory pro carb kit, if you were wondering].

It won't make the bike run too hot, it will just keep it from running too cool when just cruising around."

Red01 · « **Reply #9 on:** May 26, 2007, 10:54:08 AM »

Ok, so I had the temp thing backwards.

andrewsw · « **Reply #10 on:** May 31, 2007, 03:19:32 PM »

I put a stant thermostat in my '93 B4 and it works great. But you have to drill the little hole and also do a little file work on part of the stamping to get it to fit in just right (radiused inside corner on the stamping that holds the end of the spring up from the diaphragm doesn't quite clear the body of the thermostat holder, if you know what I mean).

A

turbofb · « **Reply #11 on:** June 04, 2007, 07:52:45 PM »

I did the Stant thermo mod today while I was under the tank.
Its Stant number 29849 in the yellow carded blister pack,in case anyone has trouble with the 13849 number than FactoryPro has listed.Its all the same unit,44MM/195* just different numbers.
Getting it to fit required just a little snip of the support arms to clear the clocking tabs in the thermo housing.No need to grind,just grab the outer 3/16" of the tabs with a needle nose plier,give it a few wiggles,and they snap off clean.The locking tabs for the poppet support assembely are still fully intact.
When I drilled the hole @ 12 O'clock I noticed that this thermostat is not a 100% sealed unit.There is actually a tiny little divit cut out of the poppet plate,right at the top to allow air to bleed.This functions the same as a jiggle pin,which would have trouble working in the vertical position that this unit sits.I still drilled the hole,just to be sure.
I noticed a lot of improvment in my around town riding and when rolling on the throttle in mid/lower gears and RPMS.There are much less "steps" to the power delivery when just riding normally.I used to get some hesitation here and there,which is gone.
I still have bad lean breakup when full throttle,around 8-9K then again at 12K.....it still wont rev clean all the way to 14K.But thats hardly a surprise since I have 100% stock carbs with just a shim under the needle.When I first dove into the carbs,I expected to find a full jet kit,since there was a Yosh system and allen head bolts on the float bowls.But,everything turned out stock,except for the 6 turns out on the screws.I ran them in to 2.5 turns and shimmed the needled up with an extra circlip,but it needs more......time for a ride down to FactoryPro for a jetkit.Like their site says,the thermostat mod is a means to an end for tuning the carbs,its not really a cure in itself.

GooseMan · « **Reply #12 on:** June 05, 2007, 11:12:36 AM »

This is gonna sound like a dumb question, but how does a thermostat help with the power delivery/carburation of an engine? I dont get it.

I thought the thermostat is there for the rad....when the engine gets too hot, the thermostat will turn the fan on...right? How does the temp of the engine change anything about the fuel delivery or anything else?

Bartjan · « **Reply #13 on:** June 05, 2007, 11:30:10 AM »

the temp of the engine has a large influence on the combustion of the mixture.

with a warm/hot engine the mixture will burn better then with a cold engine. which means that more fuel will burn (completely) and it will ignite easier (cos the fuel faporizes better and produces a better mixture and cos the mixture is alreaddy a higher temperature it needs less energy to ignite) and the combustion speed is higher (which is good)

this will have the effect that the carb settings will be easier to get right. especially if the bike is a lean, this will improve it.

i might not be spot on, but its something like this

gsxr400 racer · « **Reply #14 on:** June 05, 2007, 12:52:27 PM »

Quote from: "GooseMan"

This is gonna sound like a dumb question, but how does a thermostat help with the power delivery/carburation of an engine? I don't get it.

I thought the thermostat is there for the rad....when the engine gets too hot, the thermostat will turn the fan on...right? How does the temp of the engine change anything about the fuel delivery or anything else?

the thermostat is there to keep the motor running at optimal temperature . by holding the fluid from circulating and then opening once the temp of the stat is reached what actually turns the fan on is the fan temperature sensor.