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Author Topic: Montreal Manchild with an '81 Honda CB750K  (Read 37643 times)

Offline advCo

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Re: Montreal Manchild with an '81 Honda CB750K
« Reply #50 on: Dec 02, 2016, 13:30:52 »
Bench synch and vacuum synch are firmly on the road map, first I'm going to rebuild the buggers as the gaskets and a few of the jets look rougher than a stucco bathtub

Thanks for the link - do you own one of those things?  I'm thinking either I'll see if I can borrow one from my local shop or maybe build my own - there are a few vids showing how to rig one up with some glass bottles and a bit of know how.  It doesn't show you psi or anything like that, only that the carbs are all pumping out the same pressure (shown by the liquid levelling out in the bottles)

By the way, yesterday I broke the mirrors off my Honda CB, 'cause I didn't like it looking like I looked twee

I believe the homemade device you are referring to is for a 'wet test' that shows the actual fuel level in the carbs (for float height setting), not an actual vacuum pressure reading. You should be able to reuse all the jets, even if the surface is somewhat tarnished they will polish back up and you are much better off using factory brass than anything you'll find in a rebuild kit.

I bought one of those gauges when I was working on the GS550 i had a while back, never used it because the starter on the GS makes it an absolute pain to get to the sync ports, so I just sold it running off a bench sync LOL. The manometer setup was sold to a member here for pretty fair price. You may be able to borrow one from a dealer if they even have one kicking around, depends on how friendly you are with 'em. I use a single gauge with a 2-way valve to sync the carbs I have now (since I no longer own an inline-4).
"He broke the mirrors off his Cadillac, 'cause he doesn't like it looking like he looks back."

74 CB360 - Luna - http://www.dotheton.com/forum/index.php?topic=63294.0
82 GS550L - Tracker-ish - http://www.dotheton.com/forum/index.php?topic=67229.0 - Sold
74 XL350 - The Turd - http://www.dotheton.com/forum/index.php?topic=70252.0
Suzuki FA50 "No-Ped" - http://www.dotheton.com/forum/index.php?topic=71189.0
73 Suzuki RV125 -http://www.dotheton.com/forum/index.php?topic=73875.0

Offline The Jimbonaut

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Re: Montreal Manchild with an '81 Honda CB750K
« Reply #51 on: Dec 03, 2016, 20:13:18 »
The gauge looked like this -



Kudos to the guy - totally Macguyver'd it.  Looks like it'll do the job, but like he said it's a good idea to use glass bottles, and not to let the liquid double back into the engine.  That would be baaad.

Still leaning toward borrowing one of the real deals =)

Got the carbs finally to seat in the head boots - now all pipes are hotter than Louisiana asphalt, just like they should be.  So the cold pipe was def a carb situation - once my Randakk kits show up I'll work on rebuilding them (along with Mike Nixon's booklet on how to do it).  Moving right along =)
"I'm telling you Donnie, nuthin' but nuthin' but right"

Offline The Jimbonaut

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Re: Montreal Manchild with an '81 Honda CB750K
« Reply #52 on: Dec 05, 2016, 12:42:12 »
Well, it was definitely the carbs.  I followed some advice, opened up the vacuum cover on the offending carb, took out the slide, plastic ring, and small plastic bean-shaped cover and sprayed some carb cleaner into the 4 tiny jet ports - replaced everything and she fired right up, exhaust nice and hot.

I also realized that the rubber boots connecting the carbs to the head were really stiff, and made it very difficult to properly connect the carbs.  So I heated them up with the wife's hairdryer (about 5 mis on each), and then gently prised them off using a large flat head screwdriver.  Once off, I heated them up for about 45 mins in front of my 4800 watt shop heater, clamped them back onto the head, and the carbs popped right in there, no worries.

One small step for man...
"I'm telling you Donnie, nuthin' but nuthin' but right"

Offline farmer92

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Re: Montreal Manchild with an '81 Honda CB750K
« Reply #53 on: Dec 05, 2016, 20:32:56 »
Need to get one of those ad boivin explorer kits to get around with it now though eh?

Offline The Jimbonaut

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Re: Montreal Manchild with an '81 Honda CB750K
« Reply #54 on: Dec 06, 2016, 11:09:10 »
Ain't that the truth, Ruth
"I'm telling you Donnie, nuthin' but nuthin' but right"

Offline The Jimbonaut

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Re: Montreal Manchild with an '81 Honda CB750K
« Reply #55 on: Dec 12, 2016, 14:15:33 »
Been tearing into Rhonda, stripping her down slowly and getting to the point where I want to mock up the rear end and decide on what length suspension to fit in.  Here's how she looks now -



A previous owner chucked some 11" shocks on the back which is all fine and dandy but they ain't gonna cut it for the build I have in mind.  I want to raise the rear to give the bike a straighter look, thinking 14" - 15", but trying to figure out which size to order.

Is there a trick to playing around with the rear end to mock up how it'll look with different length shocks?  2x4's between the tire and frame?  Just want to play around with height adjustments before I order the suspension.

Thanks as always,

-J
"I'm telling you Donnie, nuthin' but nuthin' but right"

Offline Maritime

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Re: Montreal Manchild with an '81 Honda CB750K
« Reply #56 on: Dec 12, 2016, 14:22:20 »
a couple strips of 3/4' ply wood with holes drilled would give you an idea. you need to watch for chain bind/rub but I think stock your bike had 13" shocks so yo umay get to 14" and be ok
The GL Rebirth: http://www.dotheton.com/forum/index.php?topic=68337.0
CX500 Low budget Bobber : http://www.dotheton.com/forum/index.php?topic=43617.0
"Beer makes you feel the way you ought to feel without beer" -Henry Lawson
"Beer is proof that God loves us and wants us to be happy." - Thomas Jefferson

Offline The Jimbonaut

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Re: Montreal Manchild with an '81 Honda CB750K
« Reply #57 on: Dec 12, 2016, 14:41:19 »
Cool, I'll do that Maritime, thanks again, - amateur hour question but what happens if I remove both rear shocks at the same time?  Will the frame drop onto the rear wheel?  Anything I should know/look out for?  How would I install the plywood - just lift the rear end up until I can fit the plywood lengths into the shock bolts?

And how would I know what is the max shock size I can fit in? 
"I'm telling you Donnie, nuthin' but nuthin' but right"

Offline CrabsAndCylinders

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Re: Montreal Manchild with an '81 Honda CB750K
« Reply #58 on: Dec 12, 2016, 14:43:16 »
You can use this stuff but be careful because raising the rear that much will screw up the handling, these bikes are very susceptible to altering the trail which raising the rear will do.  I would keep it at the stock angle and modify the seat position to give you the look that youy want.

Brian
Lighter, Quicker, Faster.
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Offline Maritime

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Re: Montreal Manchild with an '81 Honda CB750K
« Reply #59 on: Dec 12, 2016, 14:47:19 »
Cool, I'll do that Maritime, thanks again, - amateur hour question but what happens if I remove both rear shocks at the same time?  Will the frame drop onto the rear wheel?  Anything I should know/look out for?  How would I install the plywood - just lift the rear end up until I can fit the plywood lengths into the shock bolts?

And how would I know what is the max shock size I can fit in? 

With the bike on the center stand you should be ok taking the shocks off, if you don't have one, prop it up on some blocks of wood so the rear wheel is off the ground. Like Crabs said be careful not to go to far past stock ride height, just going back to the stock size shock will fix the look for you I bet.
The GL Rebirth: http://www.dotheton.com/forum/index.php?topic=68337.0
CX500 Low budget Bobber : http://www.dotheton.com/forum/index.php?topic=43617.0
"Beer makes you feel the way you ought to feel without beer" -Henry Lawson
"Beer is proof that God loves us and wants us to be happy." - Thomas Jefferson