T Rex Bimota YB5

[stua1959]

I dont know if this has been posted previously, a review of Rex Wolfenden's FJ powered Bimota http://www.motorcycle.com/manufacturer/bimota/1987-bimota-yb5-racer-tested-on-track.html

Also a short vid about the man himself. Look out for the other very tasty FJ at 5.10 https://youtu.be/AL0ubC7GwcE

[gumby302ho]

 I wonder what they did to the FJ power plant that was in that Bimota in 1987 to squirt out those extra dozen or so horse power?

[andyoutandabout]

Much thanks for the post. What a testament to the Fj.

[Pat Conlon]

I wonder what they did to the FJ power plant that was in that Bimota in 1987 to squirt out those extra dozen or so horse power?

More than a dozen...150 rwhp is about a 30 hp bump vs the FJ stock ~120

According to the article:
1220cc 1mm overbore, JE forged pistons, Carrillo rods
ported head with +1mm valves
custom cams
Keihin 37mm CR (flat slide) carbs
Dyna 2000 ignition
4 into 1 header

Nothing too fancy....The FJ engine wakes up with headwork, cams and carbs.

Interesting that they fitted a slipper clutch to eliminate the back end chatter upon deceleration

[stua1959]

A stock FJ would be lucky to put out 100 rear wheel HP. The Bimota put out 130 so there were some mods over stock and Rex has upped that to 150 with the mods listed. Very approximate figures when you take into account differences in Dynos and a heap of other variables. The slipper clutch would be a great asset for a high performance road or track bike

[Bill_Rockoff]

103.5 at the rear wheels, with an OEM paper air filter and stock exhaust, at 22,000 miles. The pull was done in 4th gear. The readout was given in mph because the $25 "Dyno Day" special didn't include hooking up anything to the ignition to get engine rpm.

Someone joined us here to try and sell his a scruffy YB5 a couple years ago.  Would have been a nifty bike to buy, but the guy was pretty off-putting if I remember correctly; there seemed to be an underlying attitude of "your bikes all suck, here's the one you really want."

[gumby302ho]

I wonder what they did to the FJ power plant that was in that Bimota in 1987 to squirt out those extra dozen or so horse power?

More than a dozen...150 rwhp is about a 30 hp bump vs the FJ stock ~120

According to the article:
1220cc 1mm overbore, JE forged pistons, Carrillo rods
ported head with +1mm valves
custom cams
Keihin 37mm CR (flat slide) carbs
Dyna 2000 ignition
4 into 1 header

Nothing too fancy....The FJ engine wakes up with headwork, cams and carbs.

Interesting that they fitted a slipper clutch to eliminate the back end chatter upon deceleration

A 150 rwhp, wow, talk about a mover from good old 1987!!! Any idea of the loss of hp at the crank through the drive? I could guess maybe 35hp so that Bimota FJ plant could be making 185 horse power sitting on the bench. To have a dyno golden standard and go back in time and see how close the old boys figures were compared too modern times, how accurate were they in the 40's, 50's, 60's etc to the present.

[giantkiller]

According to Hank Scott my 1350 was 163hp/114ft lbs. no cams, nothing lightened. Stock carbs. On crank dyno. But. All dyno are not created equal.

[giantkiller]

My 86 1350 is at least 55lbs lighter than stock (weighing what was changed -remove) Sure is fun. But the  t Rex would be so much more.

[gumby302ho]

According to Hank Scott my 1350 was 163hp/114ft lbs. no cams, nothing lightened. Stock carbs. On crank dyno. But. All dyno are not created equal.

Are you running a freshened up stock clutch with that beast or ? Not trying to compete with you Killer but first week in Aug I came off my XR doing about 80 clicks at night and broke number 3 rib and punctured lung on my right side and broke my clavicle(collar bone). My big problem is where the clavicle broke which is right under my chin, now it sticks out and up and is causing all kinds of problems. My bigbore XR is running fairly good now but not perfect, alot more torque down low as I am sure you feel in your bigbore 1350. I am sick of taking pills, sometimes I think beer does a pretty good job on pain.  

[oldktmdude]

  Any idea of the loss of hp at the crank through the drive? I could guess maybe 35hp

According to the dyno technician that did mine, a loss of around 18% is not uncommon at the back wheel.

[giantkiller]

According to Hank Scott my 1350 was 163hp/114ft lbs. no cams, nothing lightened. Stock carbs. On crank dyno. But. All dyno are not created equal.

Are you running a freshened up stock clutch with that beast or ? Not trying to compete with you Killer but first week in Aug I came off my XR doing about 80 clicks at night and broke number 3 rib and punctured lung on my right side and broke my clavicle(collar bone). My big problem is where the clavicle broke which is right under my chin, now it sticks out and up and is causing all kinds of problems. My bigbore XR is running fairly good now but not perfect, alot more torque down low as I am sure you feel in your bigbore 1350. I am sick of taking pills, sometimes I think beer does a pretty good job on pain.  

I've the Barnet with heavy duty springs. It's been a while. Was just thinking the other day. I need to take it apart and check the clutch.

Haven't broken a clavicle yet. Would probably be bad. Pretty much involved with any upper body movement. I only take the pills to sleep. And only for the first few days. My Liver kind of exploded. Several rips, in the one that I was dead @ the scene. So my Liver doesn't work too well. I get all the bad side effects. I don't drink at all anymore either.

Hope you heal up fast.

I've found that once the bones get set enough. That they won't come apart. Usually just a few days. If I constantly move what ever is broken. Through it's full motion You'll have better use of it. And sooner than If you just do the therapy. I'm talking like every few minutes  or at least every hour. It's painful. But pain is just a tool. It's too tell you when something is fffd up. If you already know. Just ignore it.

[giantkiller]

Thanks stua for posting this. If he did mass produced them. I sure would want one... But would never be able to afford one.

[Pat Conlon]

 Any idea of the loss of hp at the crank through the drive? I could guess maybe 35hp

According to the dyno technician that did mine, a loss of around 18% is not uncommon at the back wheel.

Around 10 years ago, I recall Marsh, Marc Rittner and Gazza took their FJ's to a Dyno Jet to see who would win a bet. With a pipe, Unipods and jetting they came in around 110-120 rwhp.
Very true, not all Dynos are the same.

After the Renegade Rally where I will put a few more miles on my FJ, I will dyno mine for curiosity.
Randy's 1380cc engine is running great. I absolutely love the torque.
Leaned over, coming out of a corner, You've gotta be careful with your right hand.
She suffers no fools.

[giantkiller]

So Pat has the 1380 cured the oil consumption problem?  And I don't remember what happened to cause the rebuild?