8hp powerhead difference to the 6hp (1996, BJ6DREUC)

[Ruedi79]

Hello,
could anybody tell me the differences on the 1996-corresponding 8hp powerhead to the 6hp ?
1. I see these 3 exhaust windows each cyl. on my 6hp. How do those of the 8hp look like ?
2. Is there also a difference to the transfer ports?

 

[saltchuckmatt]

Only difference should be carburetor and intake. By the way, I have your motor as a 1997

 

[Ruedi79]

Only difference should be carburetor and intake. By the way, I have your motor as a 1997

not really - unfortunatelly. Yes, It's the main jet and the plate between carb. and reed valve. But furthermore it's this difference in the powerhead. Just check the part numbers- thy are different. On the older models- guess up to 1992- it's true what you say. I first just changed only the plate and the jet, then engine didn't run, was way too rich. So I checked part numbers and there are so other comments in the web which confirm that porting is different. But nobody can show a picture or knows how the difference is exactly.

 

[racerone]

There is a different part # for the 6 and 8 HP block.----Intake ports might be smaller.---But post the number you find on the high speed jet.----Easy to tell the difference if motor was on my workbench.___Earlier 6 hp models did not use a water cooled exhaust cover.----Earlier 6 HP had 2 reed valves / cylinder and 8 HP had 3 reeds / cylinder.

 

[Ruedi79]

There is a different part # for the 6 and 8 HP block.----Intake ports might be smaller.---But post the number you find on the high speed jet.----Easy to tell the difference if motor was on my workbench.___Earlier 6 hp models did not use a water cooled exhaust cover.----Earlier 6 HP had 2 reed valves / cylinder and 8 HP had 3 reeds / cylinder.

Not sure u understand my topic or maybe I don't understand your comment...
I have the 6hp and want to know what needs to be modified on the powerhead to get a 8hp. The "highspeed-orifice" of my 6hp is 38 and the 8hp gets the 50 (with which my 6hp-powerhead does't run at all)

 

[racerone]

Good luck with the project.

 

[saltchuckmatt]

I've heard porting is different in some models but not the 6/8. I certainly could have received bad info. So then it comes to years. Some say it changed in 92 but I have a 1991 8hp that I brought brand new and it's the newer design....so I think 1991 and a half. Again, I was told intake (restricted plate) and carb (main jet). I have a parts motor for my 8 so I'll try and check later.