yama-drag90

[river_ratj40]

im looking to build a 90 hp yam gravel bar drag motor. il put it on a 16 ft, .60 guage alum jon boat. my boat already has a tall transom, so i will probably keep a 20 mid on the motor with t/t. im wanting some ideas about some intake mods, along with porting and exhaust. i dont know if ill rig it for steering or tiller? any and all advice welcome

thanks

[Fast Fred]

this is a 70hp Yama case, 90hp is about the same but bigger,

[Carl Mc Williams]

Hey Fred,Summer has almost arrived in East Tx. We have already seen 85 degree temps. and the water will warm quickly. What you doing to that Yamaha? I should have taken pictures of the inside of cylinders on mine while I had it apart,then I might could tell. I have picked up another short shaft yamaha,this one is a 40 hp. I'ts had the head work done already,and I,m planning on doing more things to it.Maybe can get you to port later.
Thanks

[Fast Fred]

[river_ratj40]

fred,
is there some different rods to put in the 90 case that will help out with drag perfomance.

also, its a rumor, a reed cage that uses metal reeds that allows it to open up more than fiber reeds. whats ur opinion

[Fast Fred]

on the reed block thing, can't say i'd buy in to that rumor, steel reeds slap and bounce after about 6000rpms, after that thay like to brake, my self, i'd run the stock blocks, cut the ribs out, run two stage fiber reeds, no stops.

long rod makes power at higher rpms, short rod guna spin up quicker, makes more torque at lower rpms. i don't know if thares an other rod that fits,
a new rod would need a piston to work with.

[river_ratj40]

figured that about the reed stops. i have built and seen some 60 hp evinrudes, how much difference is there between a built evinrude and a built yammy. also do they make a light flywheel or do you know who could shave a few lbs off.

[Fast Fred]

you'll be alright, use red lock tight on your rod bolts, haven't seen a 90hp fly wheel in a while, did skim some off the under side of the 70hp wheel ring gear.