Any help would be appreciated

[millrod96]

Hi guys,
I need your help with this. I just installed a HPI 8000 rpm clutch spring on my FHMT. It was screaming for about 10 minutes (best performance I have ever had with it) then seized. Pull the top off and found that the piston was shattered pretty badly. I have run the truck for about 25 hours, and have the DDM Torque pipe on it. I haven't changed my oil mixture. Have a look at the pics, and if you have any ideas on what caused this I would really appreciate it. Thanks guys.
Matt

 

[drbelleville]

Sorry to hear

That is crazy. What mixture are you running ie. type of gas and oil? I would not imagine this to happen. Unless that maybe the 8000 rpm springs are not recommended for the MT Trucks due to the bigger tires? I hope someone may be able to offer a better explanation.

Good luck

 

[millrod96]

thanks for your reply drbelleville.
Running 25:1 mixture. I have always used Castrol 2 stroke oil. I am hopeful that it is just because I had a crappy quality piston in it, and after 25 hours of run time it has just had enough. I hope i don't have to take the HPI spring off....it screams with it on!
Hopefully someone can give some advice.

 

[zouz10]

Possibly a defective piston. On top of which the 8000 rpm spring might have pushed it to the limit. This is just a shot in the dark as I am no expert in engine tuning but maybe you need to richen it up a tad. One of my piston head bolts snapped a while back and ruined my whole engine because the head got too hot . Maybe this might be the solution..

BTW: I would highly recommend you get yourself an elcon adjustable clutch. They are a little pricey, but well worth it.

 

[Timmahh]

i cant see enguaging at 8000 rs being any more of a problem then when it engauged at 6500 rs with the stock spring.

thats some severe piston damage for sure though i highly doubt its related to the clutch spring.

if anything i would say its possible you were starting to get a tad lean on the needle settings ( most likely due to the cooler outside temps ) but instead of siezeing like it typically would the additional heat from running a bit leaner blew up the piston.

 

[todd217]

i agree with Timmahh. the higher rpm spring would only help. if i had to guess i would say that the 25+ hours and running at the top of the rpm range. u said it was screaming was it not screaming bf? if it was not it leaned it self out to the point that the lower oil and higher rpms and its age was just too much.

 

[millrod96]

Thanks guys. I really appreciate your help. The spring helped its performance big time. Glad I don't have to take it off. I have ordered a new piston kit, and once installed will richen the mixture a bit. Hopefully this will help.
Thanks again for all the help.