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Gsxr750 hybrid engine info required


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Yep I've built one  I used a GXF bottom end and a dot head barrel.

Primarily just cause I could as had the parts around 

I have set it up pretty standard (meaning no real high performance options) for roadability and a general daily rider done around 4000 k atm and loving it really trackable

But has performed well on the track  only losing the liter bikes down the straight.

Bearing in mind the result is only 60 odd cc's there's no real power advantage in standard trim like mine  and pulls  @ 100hp at the rearwheel and max torque comes in at @ 8000

the advantage is how it is setup to bring on the torque but if your going after power there's other options higher lift cams and stuff to suit.

The only hard thing is to bore out the rod little ends an extra 1mm in diameter for me this resulted in only a 0.3mm reduction in meat on the end 

A spacer plate can be made or bought from here (see bottom of page) http://gsxrzone.com/cranks.html but they make them to order.

and changing over the cam sprokets to suit the Hyvo Chain  and using the long stroke chain slippers

mine ended up with taking a link out of the cam chain also but I hadn't heard of that before in other builds

This is an earlier run and going a little better after some more jetting changes

 

 

dynorunShare_0.jpg

Edited by Lachie04
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21 hours ago, Ted M said:

Wow @Lachie04 the power and torque curves on that graph are bloody good flat as a witches tit (y)

After 6hr over 2 days on a dyno :tu

 

10 hours ago, dupersunc said:

Yep

The only reason I ended up going down this route was I needed to rebuild the motor anyway as at 110k the gearbox was seeing the end of it's life and somewhere along the bike rebuild I ended up with a good 99 Teapot motor so thought why not for a little extra work and it saved a complete gearbox renewal.

I was going for a daily rider that hopefully doesn't need another full rebuild for another 50 - 100 k

IF your going for bang for buck then add all the big power stuff

I have a 4-2-1 exhaust (with 1-4 & 2-3 paired) potentially a good quality 4-1 would increase the top end a bit but drop the midrange.

 

 

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11 hours ago, Slabbyruss712 said:

Do you have to use the short stroke block, can't you just bore the long stroke block to suit 

yeah you can go find all the bits to overbore the longstroke but then it wouldn't be a "Hybrid"

I think the general ethos of hybrid is bolting something together which is generally within the stress tolerances of the OME motor

Edited by Lachie04
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I'm putting one of these back together at the moment.

It was given to me by a nice bloke in Barnsley last month.

It was a Bandit 600 cases, crank and rods with late gsx750 70mm pistons and barrels making it a 750.

I have early 73mm barrels and pistons on the way to make it 814cc.

Having read through the interchangability thread re oil burner motors it seems the little ends are different diametres or am i reading it wrong???

If they are different diametres are there compatible rods available or is getting the original Bandit rods machined the only option?

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On 6/13/2019 at 9:34 AM, Lachie04 said:

Yep I've built one  I used a GXF bottom end and a dot head barrel.

Primarily just cause I could as had the parts around 

I have set it up pretty standard (meaning no real high performance options) for roadability and a general daily rider done around 4000 k atm and loving it really trackable

But has performed well on the track  only losing the liter bikes down the straight.

Bearing in mind the result is only 60 odd cc's there's no real power advantage in standard trim like mine  and pulls  @ 100hp at the rearwheel and max torque comes in at @ 8000

the advantage is how it is setup to bring on the torque but if your going after power there's other options higher lift cams and stuff to suit.

The only hard thing is to bore out the rod little ends an extra 1mm in diameter for me this resulted in only a 0.3mm reduction in meat on the end 

A spacer plate can be made or bought from here (see bottom of page) http://gsxrzone.com/cranks.html but they make them to order.

and changing over the cam sprokets to suit the Hyvo Chain  and using the long stroke chain slippers

mine ended up with taking a link out of the cam chain also but I hadn't heard of that before in other builds

This is an earlier run and going a little better after some more jetting changes

 

 

dynorunShare_0.jpg

What carbs do you run?

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1 hour ago, GSXR4814 said:

What carbs do you run?

 RS38's. I'll probably switch back to the BST36's  and put the Flatslides on the 1052 I'm rebuilding so will be interesting to see how the 36 CV's differ, but that's a while off yet. Potentially the RS38's could be a little big for this motor.

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1 hour ago, GSXR4814 said:

I'm putting one of these back together at the moment.

It was given to me by a nice bloke in Barnsley last month.

It was a Bandit 600 cases, crank and rods with late gsx750 70mm pistons and barrels making it a 750.

I have early 73mm barrels and pistons on the way to make it 814cc.

Having read through the interchangability thread re oil burner motors it seems the little ends are different diametres or am i reading it wrong???

If they are different diametres are there compatible rods available or is getting the original Bandit rods machined the only option?

The B6 and the longstroke have the same little end diameters the short stroke is 1mm bigger I think frankestiens guide says 20mm but actually 19mm

 

I dont know of any compatible rods

I've seen a thread were the guy did it with the B6 cases/bottom end

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4 hours ago, clivegto said:

I have a lightened 1052 crank which I plan on putting in a 748 short stroke bottom end probably with 1127 decked barrels & pistons with the 748 short stroke dot head.

Sounds interesting I presume you'll be expecting it to spin up faster I've been contemplating running mine with no starter clutch to reduce the parasitic drag (going to be a race motor anyway)

I guess you'll be running into this also with the short stroke case I  had heard about having to skim the rib

WP_20190513_19_27_13_Pro.thumb.jpg.c65df942292d67f790b5a32f200ef83a.jpg

This pic shows the 1052 rod end moving away from the short stroke case oil gallery. With the cyl. block just sitting here is very close, with it torqued down potentially will hit.

I haven't measured the actual clearance and don't know it would be of any benefit anyway.

Like others, for the sake of it, I will probably grind about 2mm out. In looking at it there seems to be about 5mm of "meat" above the actual oil gallery passage

I'd be interested to see what the old 1052 case looks like in this area did they change the oil passage routing???

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Hmmm.....my 73mm barrels and pistons turmed up today.

They were listed as 1992 GSX750F.

My current 70mm barrels are approx 75mm high...new 73mm ones are 69.5., these dimensions are approx as the battery is flat in my vernier so using a tape measure.

Little ends are bigger and centre of little end to top of piston is greater by about 3mm???

Does this sound right?

I didn't think 1992 GSX750F was short stroke which these parts seem to be?

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