Rossi Powerhead

[chriscarbon]

jerry,

the older 6 bolt crank is longer than the new four bolt crank. three years age the older crank was approx 35.00 if memory serves me right. dave at hyperformance would have current cost & i thought he recieved some of the new ones.

chris

 

[Jerry Wyss]

Thank You Chris!, I'll dial Dave an see what he's got.

 

[oldlugs]

Just a thought for you guys running Rossis... Take a look at this sleeve drawing, and measure the OD of your sleeve. The Maranello sleeve is the same Rossi part # as the Rossi Piranha inboard. The Black Magic sleeve has the same dimensions as well, with less timing for more bottom end, but it may still be a better breather than the current Rossi OB sleeve. I don't know if these can be a substitute for what you have, but it's worth checking into. Just a thought...

Sahak sells both of these sleeves in stock and massaged forms at decent prices...

 

[Jerry Wyss]

Mike,

I'll tell you I haven't seen a motor take so long as these Rossi's to break in. People told me its takes a gallon of fuel before they start running and they right. I have two hours of run time and its still not broke in, but getting close. You heard me right, not broke in yet. Its still tight. So your button head looks somewhat close to a K&B head, yes or no? You can't find much on the internet about these motors and I wonder why.

Do you know? I've searched and came up with nothing. If you have any good good web sites about them could you please turn me on to them. Let me know how your break in process is coming along.

Chuck

I just ordered a 3.5 o/b powerhead for me and a crank for Kris Flynn. The powerhead is $189.95 and the crank is $79.99,,, that's a good price for an O/B powerhead, yeah?

Just punch in "hyperprod" on Google and hit 3.5 O/B Powerhead , then "Home", that'll get you there.

Does anyone know how well the Irwin Plastic lower is working?

Anyone mount this powerhead up to one? :huh:

Jerry

 

[Jerry Wyss]

can anyone else that has the four bolt silver head rossi 3.5 tell me if theirs came stock with a "turbo" plug style head? I just recieved the one I got from ebay and it has a turbo head. It also has four head bolts, which I found strange because I thought it was suppposed to have more than the gold head version...

~James

Hey Top, My 3.5 Rossi O/B powerhead came today and it's funny, the picture on Hyperprod

web site shows the 6 bolt Goldhead. What you get is just what you have James only it comes

in an "AXE Motor Rossi" box that is a much smaller box than the one yours came in.

I called Dave at hyperprod and he said that they haven't changed the Gold Head picture but

what I got was the new one,,,

I do believe it's the car engine case as it has the "oil hole" going to the front bearing.

The headbutton has the turbo deal and the bubble volume is about .21cc up to the begining

of the angled squish,, looks like we have another Thunder Tiger headbutton problem. I assume

that same button is used in the car engine as well.

I was able to make the TT run quite strong with much smaller boost and transfer area's than

this one has, but I did have to make low volume buttons to get the "Man" out of it.

This one looks like it will get the same treatment, 'cept without the turbo plug deal!

Oh, and all that literature that comes in the box? None of it is any good for the engine

that comes in the same box. It has 4 different engines shown (in English) but none of

them are this engine,, waste of space!

JW

 

[Jerry Wyss]

Hey "TopFuel443", James, did you check the timings on your Rossi?

I'd like to have someone to check with,,

I'm getting:

160 degree Ex port

120 deg transfers

30deg opening ABDC

60deg closing ATDC

I put .015" sleeve shim in and it raised things 5or6 degrees :huh:

The induction timing looks Ok but I'd still like to extend it to 65 deg close.

It has a weird ass carb neck size of 16mm,, for a .21 that seems big but

I have a fix for that with the O.S.20J,,which I have perdy good luck with.

Whata'ya think? Anyone?

 

[topfuel443]

Jerry, I ran the numbers but dont remember what they all were, I just finished one motor yesterday, now ive got the back up motor to do. I am pretty happy with it at this point, although it took quite a bit of work to get it where I wanted it. I had Rod do a carb for me, its one of his super duper black carbs and he made the adapter for it.

I do remember raising the exhaust up to 176 degrees, it was way to low for what I wanted. I had to do quite a bit of work to match the intake and boost ports to the case, they were the worst I have seen yet, even worse than the K&B 3.5.

one of the major things I had to do was get the head button straightened out. I ended up modifying a CMB TT (old gold head) head button to .18 cc and had to turn down the O.D. to make it fit inside the water jacket... about the only thing I didnt have to do was the bolt pattern was perfect. I also had the turn down the squish band area as it was too tall, and I put our special "OvalExpress" taper on it. :unsure:

I took about 5 thousandths of the top of the sleeve and got the head clearance to .007 with a .004 shim installed. I relieved the top of the case where to sleeve sits, cut a little on the crank (thats a hard ass crank!!) I relieved the rod bushing, and got a good fit on the piston/liner. That was one of the tightest P/L's ive ever seen. disasembled all of the bearings, cleaned that MACK dump truck grease out of them and reassembled them. The PTO looks pretty solid also, nice unit.

I will run it pretty soon to see if its got any potential... I sure hope so after spending 3 days on it. Ill try to post a pic.

~James

yeah, that 20 J is a nice little carb, let me know how it works.

 

[Jerry Wyss]

Yeah that button is out'a here :blink: , the Thunder Tiger button looks good next to it,

shows how far off it is. I still have to spin-up a new one for the Rossi but I could alter

a stock TT button and get in the ballpark.

Before I got my lathe I had a friend cut the neck down on a 20J to fit in one of my

mod TT's and he overcut it about .011",, I was pissed. But as it turned out I took

that carb and J&B welded a short section of 1/2" Type "L" copper water pipe on

there and it fit the Rossi perfect!

There is also some K&S brass tube that will go over the 20J neck and is enough

to fit the Rossi throat too (16mm OD X slightly over 15mm ID

JW

 

[topfuel443]

Here are some pics of the almost finished product. Now Im just waiting on the postal service to deliver my irwin nitro pipe that I cut into a J-pipe and had Dave Roach weld it for me. I think it will compliment this combo well...

mounted on a new lawless from Mark Sholund:

It was "engine building weekend" here in the shop....

still got one more Rossi to mod for a back up:

right side shot

good shot of the geraghty carb and the oiler system

does anyone recognize the tunnel that this rossi is mounted on??

 

[Jerry Wyss]

That looks like my work Table :lol: Lotta "Irons" in the fire,, Looks good!

I'm going to use the REK lower for testing in the winter also am looking into

pickin'-up one of the Rossi inboard pull-start motors crank (same motor) to

adapt to the TT lower,, see if I can't find some jizz in one of these motors :lol:

 

[topfuel443]

Yeah, I feel your excitement. Its fun making these things go... fun and aggrevating at the same time. but it keeps us busy right?

If you look in the one motor picture, you will notice my other set of projects... its has to do with the OS. got tired of the nickel chipping off....

~James

 

[Jerry Wyss]

I think I see an "RG-X" car engine sittin' there, but man they gotta short sleeve in'em, yeah?

 

[Ronald van Essen]

Here are some pics of the almost finished product. Now Im just waiting on the postal service to deliver my irwin nitro pipe that I cut into a J-pipe and had Dave Roach weld it for me. I think it will compliment this combo well...

does anyone recognize the tunnel that this rossi is mounted on??

I do recognize it, it's from the dude with the long hair...............LOL

Ronald.

 

[topfuel443]

Jerry, a little lathe work here, a little lathe work there... the port sizes and shape are identical. the OD of the sleeve has to be turned down and material removed from the underside of the lip that the sleeve sits on and you have a perfect chrome plated sleeve, stock porting and a hell of a lot cheaper. (you can buy the entire engine on ebay brand new for around 70 bucks..., The sleeve isnt all you can use either...

Ronald...Ding ding ding!

~James

 

[topfuel443]

Jerry, maybe this will help. hard to get a good shot to show how good they match, but you get the idea.

The new OS XM sleeve on the left, the new OS RG sleeve on the right.

Bore, stroke, port size/shape all the same. The rods are the same. the pistons are a little different but you use the RG piston with the newly cut sleeve.

~James

 

[Jerry Wyss]

Thanks for the pic Top, I bought a RG-P-X to see if it would adapt to the TT PTO, didn't look

like the whole motor would exceed the perf of the TT so I set it aside.

I noticed it had a short sleeve and was too big to fit in the XM, but Eric B. got two seasons

out of his XM sleeve running 67% in stock form so I didn't persue it. Gawd, you just generated

something else for me to do :lol:

So you turn a taperd piece of aluminum for the top of the sleeve and run a live center in the

bottom from the tail stock??

You RE-Painted My "TORCO" Cowl Back There,, You Really Are Sick! :angry: , No,

NO, I guess you didn't :lol:

 

[Tim_Duggan]

does anyone recognize the tunnel that this rossi is mounted on??

Yep - it did a stint "down under" about a year ago. Well travelled boat!

 

[Ronald van Essen]

James

I see in one of the pics that you have that special o/b pipe back from welding....

Let us know how it works.

Nice pics and thanks for showing what you did on the engiens.

Ronald.

 

[topfuel443]

Jerry, its kind of hit or miss with the XM, ive run nine gallons through one before it started shipping, and I have one here that has less than a gallon and is chipped worse than the one above. they still run decent when chipped....but.

Ive got three engines here and its a good way to refresh all of them.

I havent turned a RG sleeve yet, I just found a lathe to use at a friends house over here in Germnay last week. The first RG sleeve I sent back to the states to have my buddy turn it. I assume he made a tappered holding tool, as its what I would have done.

nope, didnt repaint the Torco cowl, its just another old 3.5 cowl sitting in front of it.

Tim, thats the one!

~James

Ronald the pipes you see in the pics are from a few years ago. Pipes that i cut and had welded.

The one that Dave has done for me has not come in yet.

~James

 

[Jerry Wyss]

Yo Top! I have a small task to ask you if I may. One of the hardest things with some of these

"squeeky" tight piston/sleeve fit motors is to get a headspace measurement when they're

new. Both the Mac and this Rossi motor are so hard to get TDC to get that measured.

Could you measure for me the "thickness" of the part of your button that goes into the sleeve?

and @ what headspace? (you don't have to if you'd rather not)

I measured the Mac mathmatically and was off by .011", I found out after I ran it a while.

I'm going to make a couple buttons for it next and thought I'd give you a little more trouble

instead of gettin' out the heat gun, rag & channel-locks.

You were right, that crank "is" hard but I did get a 65 degree closing on the crank.

My exhaust port timing ended up @ 181deg, but with .015" sleeve shim in there I

can pull that down if'n the Rossi don't like it.

Nice lookin motor really, for the price, everything looks to be well made,, all it has to do

is exceed the perfomance (and reliability) of my mod TT's to get my vote.

JW