Shimming Waterpump Impellar

[Honda 250r 001]

Hey guys, i was just wondering how close the impellar fins should run to the defuser tin. Would it be good to shim the impellar twords the tin if its too far away? The tin is in great shape, and the impellar is like new. So i cant see anything being worn here.

[twopump78]

is your water pump not pumping? or is your bike boiling over? if it's getting hot check the radiator cap.

[Honda 250r 001]

Originally posted by twopump78
is your water pump not pumping? or is your bike boiling over? if it's getting hot check the radiator cap.

cap is good, seals good and has pressure. But the waterpump doesnt flow the greatest.

[C-LEIGH RACING]

Dont see any problem doing that & for sure, closer the impellar is to the defuser tin less coolant can bypass the blades.

I would clay the area between the defuser tin & impellar so you would have a measurement & know the amount of clearance between each other once the cover is bolted on. Dont want it touching any.
Neil

[Honda 250r 001]

I tried shimming it. We will see how it goes. I just put a small copper washer on the back side of the impellar. Tightened the gap a little. I know this can be important on cars. Hopefully my dam 250r will keep under 200 now.

Thanks neil!

[C-LEIGH RACING]

It is also important, the fin area on the outside of the radiator is clean & not plugged up with silt & restricting air flow through them.
Fine dirt can get into those little openings, plug them up then you end up with a hot spot.
On the inside of the radiator, those little tubes surfaces can corrode down inside where you cant see & the metal cant transfer the heat through for the air flow to carry the heat away.
Lot of different things can cause a 2 stroke to over heat, finding out what they are & correcting them is more important than riding.
Neil

[Honda 250r 001]

Originally posted by C-LEIGH RACING
It is also important, the fin area on the outside of the radiator is clean & not plugged up with silt & restricting air flow through them.
Fine dirt can get into those little openings, plug them up then you end up with a hot spot.
On the inside of the radiator, those little tubes surfaces can corrode down inside where you cant see & the metal cant transfer the heat through for the air flow to carry the heat away.
Lot of different things can cause a 2 stroke to over heat, finding out what they are & correcting them is more important than riding.
Neil

What do you reccommend to clean the inside of the radiator without taking it to a special radiator shop?

[croat1]

^^^^^^dude!!!!!do it fix it right the first time. take it to a radiator shop

[Honda 250r 001]

Originally posted by croat1
^^^^^^dude!!!!!do it fix it right the first time. take it to a radiator shop

Dude, i would, but im going on a big dune trip this friday = not enough time. :/ It flows good and the fins are clean. And when i look inside it looks clean. I was just going to see if anyone had any at home things that work well. Just incase there is corrosion i cant see.

[C41Xracer]

not enough time? dont cut corners or you'll get screwed in the end

[Honda 250r 001]

Originally posted by C41Xracer
not enough time? dont cut corners or you'll get screwed in the end

Rad looks clean, flows good. Ill take it off, and see if i can get it to a rad shop and back before thursday.

[atvmxr]

you headed to LS this weekend?

[Honda 250r 001]

Originally posted by atvmxr
you headed to LS this weekend?

Yes, Were leaving friday. R u headin out too?

[C-LEIGH RACING]

If the radiator looks real clean inside at the cap area, no deposits caked up, its probably ok down through the flues, so no need to waist time taking it to a radiator shop.

If it was corroded inside, there would be some signs of it at least a small amount right under the cap & would be easy to see.

You get a 250R from somebody & realy got no idea what the owner before used for coolant, reason I'm say check it out good.
Suppose to use distilled water fixxed 50/50 with antifreeze as coolant. That way no metals will be in the water to cause corrosion like it is in regular tap water.
While you have it off, use a water hose & flush water through it both ways, back flush to make sure nothing settled at the bottom.

Hold the radiator up to a light & look through the fin areas, make sure you can see through all the little slots.
Where ever theres silt plugging up the slots, stopping air flow, it cant cool the coolant in those areas.
Neil

[Honda 250r 001]

Originally posted by C-LEIGH RACING
If the radiator looks real clean inside at the cap area, no deposits caked up, its probably ok down through the flues, so no need to waist time taking it to a radiator shop.

If it was corroded inside, there would be some signs of it at least a small amount right under the cap & would be easy to see.

You get a 250R from somebody & realy got no idea what the owner before used for coolant, reason I'm say check it out good.
Suppose to use distilled water fixxed 50/50 with antifreeze as coolant. That way no metals will be in the water to cause corrosion like it is in regular tap water.
While you have it off, use a water hose & flush water through it both ways, back flush to make sure nothing settled at the bottom.

Hold the radiator up to a light & look through the fin areas, make sure you can see through all the little slots.
Where ever theres silt plugging up the slots, stopping air flow, it cant cool the coolant in those areas.
Neil

Hey Neil, thanks for all the help here. Just let me add that i put the inline temp gauge between the cylinder head, and the radiator. So i really havnt checked to see how much the radiator is cooling the water. What should the water temp read coming right out of the head?

[C-LEIGH RACING]

I dont think theres any locked in temp amount, because so many R's across the US in different areas.
You know water boils at 210*, so anything under that should be ok. 180* would be a good degree to shoot for.
You need to be sure you have a closed system as well, closed so presure can build up & that has an effect on how good the system cools.

Case in point, had a rider one time left his cap loose on the radiator, guess who seized up on the 4th hot lap of practice, so it needs that presure in the system for the coolant to do its job.
Neil

[Honda 250r 001]

Originally posted by C-LEIGH RACING
I dont think theres any locked in temp amount, because so many R's across the US in different areas.
You know water boils at 210*, so anything under that should be ok. 180* would be a good degree to shoot for.
You need to be sure you have a closed system as well, closed so presure can build up & that has an effect on how good the system cools.

Case in point, had a rider one time left his cap loose on the radiator, guess who seized up on the 4th hot lap of practice, so it needs that presure in the system for the coolant to do its job.
Neil

Alright sounds good, Ill shoot for that. Sometime before thursday night ill have it running and see how my new waterpump flows and if it cools better.

[All250R]

Originally posted by Honda 250r 001
Alright sounds good, Ill shoot for that. Sometime before thursday night ill have it running and see how my new waterpump flows and if it cools better.
How are you measuring how it flows before and after?

[Honda 250r 001]

Originally posted by All250R
How are you measuring how it flows before and after?

I wont know unless the change is enough to see when i pull the radiator hose off

[All250R]

Originally posted by Honda 250r 001
I wont know unless the change is enough to see when i pull the radiator hose off
To be honest, and for what it's worth, I'm having trouble seeing that fixing a design that's been around for a long time successfully is going to solve your problem - the design being the impeller clearance. IF it helps flow first, and if it amounts to a cooler engine second, my money would be on it alleviating the symptom some, but it's not a fix to the real problem.

I know you're pressed for time, but if you had it, as I mentioned it in your other thread, I would check piston to cylinder clearance to start with, check for air leaks, bomb the radiator with a hose or sink and see if it flows well out the bottom hole. Make sure the coolant mixture is adequate. In so cal where it doesn't freeze I usually run 7:3 water to coolant, since water sheds heat better than antifreeze. Make sure the head gasket isn't leaking (though you'd probably notice a loss of coolant by now I'm assuming). If all else fails, run richer jetting. Try a cooler plug like a NGK 10 series, or at least a 9. I'm also an unofficial fan of the OEM radiator shrouds. In my head the scooped ones cause cross turbulence and choking where what you ideally want is air to flow perpendicular through the radiator unimpeded.

[Honda 250r 001]

well when i started out the first day, it was lean, dam near seized the piston... no compression. So i took the head off and cleaned out the ring groove and honed the cylinder, and threw it back together... +3 sizes on the main and were good to go once again...

Well Ive come to the concusion my ESR temp gauge is wrong. I looked down at the dunes multiple times and the gauge was pinned at 255-260... By then the water would have been boiling... I ran it balls to the wall all day and when I checked at night, the water was still full.