VFR Oversized Bore Mod

I've been looking into boring out my '01 VFR 800 to 870cc...Getting about 20+ more HP and 8+ more ft-lbs torque. (I'd buy a 2nd motor to play with). A company out of Quebec, Canada does it for around $1600.

http://www.dynamohumm.com//VFRMOTOR.htm

Anyone had experience boring out their VFR?

-Eric Johanson
proerj@yahoo.com

 

May want to be carefull. The pistons and cylinder walls (rings) have very tight tolerances on the Honda V4, and are both made from aluminum and composites to have the same expansion rate. Meddling with either could do some serious damage to the lower end of the engine.

 

Thanks for the advice. I've talked an engine builder who's worked on other engines about this specific issue. What he said (W/o experience on V4) is that he uses a .004"-.005" interference fit for the sleeves. The major factor is that some engines have the sleeves cast into the block, so fitting a sleeve may not have the same heat transfer characteristics. Do you know much about this?

-eric

 

Howdy,

There are quite a few folks that have done the kit from Dynamo Humm. Ask on the big VFR mailing list and I am sure you will get responses from several of them. Here is the address for the list in case you are not familiar with it:

http://www.cs.wisc.edu/~john/vfr-list/

Good luck! Let us know how it goes!

Adios,

 

Scott:

Thanks...I'll check it out. I've been trying for several months to get in touch with someone who's done it on an 800cc w/o any luck. Dynamo Humm says they've only done 3 total. From what I understand, there's been quite a few done on the older 750 blocks, but they don't use the cast in sleeves. Wish me luck. By the way, I've found your website to be very helpful.

-proerj

 

Scott:

Finally got a hold of Steve R. out of New York. Thanks for the help.

-eric