Author Topic: 550/650 hybrid or 650 big bore HOW TO (Read 110832 times)

spdygnzlz · « **Reply #200 on:** July 19, 2012, 02:07:29 pm »

Can the 550 carbs keep up with this setup if I use the 550 bottom and 650 top with no boring out? The engine I picked up has no carbs with it so I'll have to reuse the 550 carbs or get early 750 carbs as i'm having a hard time finding 650 carbs for the '80 engine.

Tintop · « **Reply #201 on:** July 19, 2012, 05:08:19 pm »

I have a set of the 77/78 750's with the accel pump. Their nice and clean but probably should get kits as they've been sitting for a while. PM me if your interested.

Scott S · « **Reply #202 on:** November 18, 2012, 03:13:05 am »

What are you guys doing for carbs? I'm going today to pick up a pile of 650 stuff. I'm thinking of doing a complete engine swap, but need to know what to do about carbs.

There are some CV carbs included in this pile 'o' stuff, but not sure of condition yet. I have 550 carbs. Would I need to source the non-CV 650 carbs? I see 750 carbs mentioned quite a bit....any particular years or #'s to look for?

paulages · « **Reply #203 on:** November 19, 2012, 10:42:21 am »

For a stock 650 engine, stick to stock carbs. If the engine is a '79-80, then 750 carbs will fit. '81-82, gotta use the CVs.

spdygnzlz · « **Reply #204 on:** January 01, 2013, 07:38:58 pm »

Hey Paul,

When you did the switch to the 650 clutch gear, what did you do to correct for the change in ratio? What was your front/rear sprocket choices? You went with a 520 chain conversion?

Thanks!

Bill/BentON Racing · « **Reply #205 on:** January 02, 2013, 05:51:11 pm »

I used 69 model 750 carbs on roadracer.Easy to change needle position! The linkage carbs that came later worked fine,but if I remember had to clearance a little on frame and maybe tweek linkage? Been a long time now.Just sold Greggo my last 2 sets of '69 carbs. I do have several sets of linkage carbs anyone interested.Just let me know.Bill

paulages · « **Reply #206 on:** January 09, 2013, 10:50:05 pm »

Quote from: Bill/BentON Racing on January 02, 2013, 05:51:11 pm

I used 69 model 750 carbs on roadracer.Easy to change needle position! The linkage carbs that came later worked fine,but if I remember had to clearance a little on frame and maybe tweek linkage? Been a long time now.Just sold Greggo my last 2 sets of '69 carbs. I do have several sets of linkage carbs anyone interested.Just let me know.Bill

I'll have to double check my final drive ratios, but it's easy enough to find online gear ratio calculators, where you plug in the ratios of the primary, all the gears, clutch gear, etc. and it helps you calculate the final drive ratio.

spdygnzlz · « **Reply #207 on:** January 10, 2013, 08:02:22 pm »

I did the search and found your old post asking the same question I did regarding the 550-650 differences. You came up with 16/39 and after going through an online ratio converter, that looks to be almost the same final ratio as a stock 550. I think it even showed the differences in rpm at only about 100rpm.

Scott S · « **Reply #208 on:** July 17, 2013, 09:20:40 am »

Paulages, you have a PM.

Looks like I may try this soon. I have a 550 and a 650 engine and both need freshening, so.....

sinister902 · « **Reply #209 on:** July 29, 2013, 09:43:17 am »

well, I've decided to build TWO of these hybrid motors. I have two popped cb550 motors that have lost compression in the top end, two cb650 motors(one '79 and one '80) and I have scored two sets of cb750 cylinders on ebay, and the cruizinimage 836kits for both motors. I'm going to start a build thread....I'm hoping paulages is nice enough to chime in and let us in on his dirty little secrets for small details he didn't outline here or in his 735 rebirth thread on things to do while into this build to make improvements where he found weaknesses on his quest to make this motor as awesome as he has in his bike. I'd love to be able to take his findings and make a nice full blown step-by-step how-to with pictures and actual machining specs so any other SOHC4 member can replicate this awesome engine build.

-I know he modified a more modern chain tensioner to work, but not sure how
-I know he did some transmission mods
-I know he added some other small upgrades inside the cases but no idea what/how/where.

would really like to build these two motors for the two bikes I have and have them be reliable and as much of a blast as paul's sounds to be!

GV1390 · « **Reply #210 on:** July 30, 2013, 08:19:12 am »

Two motors you say ehh? Wonder who the other one is for -_-

spdygnzlz · « **Reply #211 on:** September 13, 2013, 12:13:30 am »

Any chance you have a pick of the modification required to fit the 750 carbs? I know the cable hanger needs to be bent/tweaked but I'd love to see the proper solution before bending mine.
thanks!

Godffery · « **Reply #212 on:** September 19, 2013, 08:09:50 am »

This is an awesome thread, thanks for all the tasty tech!

taggat · « **Reply #213 on:** November 11, 2013, 12:13:48 pm »

Ive been reading this all day and I thank you guys and gals as its very informative.
Im taking cliff notes as this info is buried in here.

Just so Im clear though the cheapest hp gain for your buck is to take a cb550 bottom end, put the cb650 top end on it with some early 750 pistons "~61mm", shave the dome until your reach your .027 of squish and use the early 750 carbs if youve got a 79-80 650 head or the stock cv's for 650 for a 81-82 and your on your way to smoking the 750's?

no hp gains but better alternatives are the use of the cb650 clutch, oil collector and sump pan.

Please correct me, Im going to a friends tomorrow to pick up a seized 82 cb650 I believe and I have a 76 cb550 with no compression.

mundi · « **Reply #214 on:** December 23, 2013, 01:54:12 am »

Anyone's know how to get in contact with paulages? I've tried to PM him with no results...

sinister902 · « **Reply #215 on:** December 26, 2013, 08:56:24 am »

taggat, for what it's worth I thought what you wrote to be true as well, but I have a 79 cb650 motor sitting here now and a set of early 750 carbs, and they don't line up as I thought this thread to describe.....

I have a 550 bottom end that I've just cracked open due to loss of compression, going to use the cases and trans from this and use the rest of the 650 motor on here....I have an 836cc kit and some 750 liners ready to go as well. decided to go fuel injection and have bought some cbr600rr throttle bodies.

mundi · « **Reply #216 on:** February 11, 2014, 04:02:03 pm »

Sorry to do this in this thread again, but has anyone got an email for paulages that he checks regularly? I'd like to get him to build a motor for me if he's keen. Thanks

turboguzzi · « **Reply #217 on:** February 12, 2014, 12:12:46 am »

Quote from: mundi on February 11, 2014, 04:02:03 pm

Sorry to do this in this thread again, but has anyone got an email for paulages that he checks regularly? I'd like to get him to build a motor for me if he's keen. Thanks

PM me your email and i'll fwd

taggat · « **Reply #218 on:** February 14, 2014, 06:22:05 am »

If anyone is interested, I have a complete 81 cb650 motor, exhaust and carbs.
78 cb550 bottom ends in peices, cases split.
Located in Anderson, In. 46011. 150 bucks

papadapalis · « **Reply #219 on:** February 23, 2014, 09:02:30 am »

Has anyone completed this using a cb500 bottom end? I found one really cheap locally and im wondering if I should pick it up or try to find a 550 bottom end.

Sent from my SCH-I535 using Tapatalk

redrider736 · « **Reply #220 on:** July 02, 2014, 01:08:27 am »

Great thread, WAY OUT of my league though !! Baring electric mods could you not just drop in a 79-82 Cb650 motor with a Dynoman DMP674 street kit, 750 Carbs and call it a day ??

Godffery · « **Reply #221 on:** July 05, 2014, 06:36:07 am »

Quote from: redrider736 on July 02, 2014, 01:08:27 am

Great thread, WAY OUT of my league though !! Baring electric mods could you not just drop in a 79-82 Cb650 motor with a Dynoman DMP674 street kit, 750 Carbs and call it a day ??

Yes, I've seen it done hear on the list and as I understand, it goes in rather easily.

Tews19 · « **Reply #222 on:** July 07, 2014, 01:50:17 pm »

Any idea what the HP is with the dyna man kit?

Godffery · « **Reply #223 on:** July 09, 2014, 08:04:24 pm »

No idea; that sounds like a question for the dyna man.

spdygnzlz · « **Reply #224 on:** July 09, 2014, 08:29:55 pm »

I did this conversion with the dynoman 674 piston kit, mildly ported head, and cr29 carbs. Still trying to find someone in the bay area who can dyno and tune the bike without costing over 1k.

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Author Topic: 550/650 hybrid or 650 big bore HOW TO (Read 110832 times)