21bb rebuild time?

[Renegade88]

OK I have run through 18 litres of fuel in my stock 21bb. Yesterday it just started to run very slugish and took a long time to reach top speed. Is this normal after 4.5 gallons? Starting is getting difficult as well. Should I rebuild or get the new OS?

 

[Çh®i§tiªñ]

Could be. While off, try turning the flywheel to the left (make sure glow plug is in). If you can turn it a full rotation with no resistance or very very very little, then yes, its probably rebuild time.

Which O.S.?

 

[Renegade88]

O.S R-gx I have only being reading good things about these engines

 

[Çh®i§tiªñ]

They are great engines!

Did you try checking the compression by rotating the flywheel?

 

[Renegade88]

dont have a compression tester?

 

[Çh®i§tiªñ]

you dont need one

With the glow plug installed
Turn the flywheel counterclockwise and see if it provides decent resistance. You should hear a slight pop when the piston passes by top dead center.

If it just spins and spins then yes itsd rebuild time.

 

[Renegade88]

Whats the average amount of gallons before anyone has rebuilt there 21bb?

 

[Çh®i§tiªñ]

It will depend on how hard you run it and how lean. I've seen .21bb's brought into the shop at less than a gallon and I've seen them upwards of 6-7 gallons. There may be ones out there with more. Guess it just depends on how hard you run it.

 

[Renegade88]

I stripped the engine last night and found a nice groove on the piston about a hair width deep and a bit off the top of the piston aswell, I guess my engine is toast.

 

[Çh®i§tiªñ]

I would say so.....

 

[Renegade88]

LOL I am still waiting for the rebuil kit from Tower, its been almost six weeks since I orderd it. I am installing a machined alluminum head aswell that HPI manufactures. Can I expect lower temps with this head, and by how much?

 

[Çh®i§tiªñ]

I would estime 20-30 degrees when tuned for performance at most. Just enough and not too much :thumbuP:

 

[Renegade88]

Thanks I will update when the stuff eventualy arives