Will's 79 Single Carb Conversion

[wbishop]

As the story goes, I've got a third generation family bike that I got from my dad. I traded an 85 Cadillac Sedan DeVille to him for it. I paid $300 for the car, and put some money into it over the years for maintenance, but it lasted me about 5 years. The bike has sat in the garage at my Dad's for the last 5 years or more with fuel in the carbs. It was varnished to the point where I couldn't get the throttle linkage to budge.. anywhere. I looked into doing the Randakk rebuild on them, but after I pulled them apart I found some stripped screws and knew it'd be more work than I was comfortable doing. So after doing a lot of research on single carb conversions, I decided I wanted the low maintenance and easier alternative.

I've learned a lot from everyone here just by reading up on it and do not take credit for any of this. I'm no engineer.

I'm converting using Tom's Carter Weber carb (32dft) and the VW intake manifold. I'm using the stainless steel grab bar for my runners, but will be connecting them to the intake elbows on the heads. (just using it as SS Pipe essentially) The OD of the grab bar is 1.25", and based off what I've read, this seems to work well.

I ordered my parts last week and just got them in this morning and I've already hit a road block. I ordered the VW Type 3/4 Manifold from jbugs. https://www.jbugs.com/product/3241.html

I pulled out my Carter Weber carb to bolt it up and test fit everything. The manifold seems to be different than the ones that I've seen on here. The Carter Weber Carb bolt holes don't match up with the manifold. I'm attaching some pictures to show what I mean. Basically what I'm planning on doing is turning those circle bolt holes on the carb into ovals, or slots to make things line up. I hope this makes sense. I'd really hate to send the manifold back since I've been looking forward to this for months. I had planned to spend the whole weekend working on the bike and getting it running.

Thoughts? Ideas? Should I ship the manifold back? Has anyone else experienced this issue?

 

[Ansimp]

If you look through Dan's early threads you will see how he and others made the studs and manifold line up.
viewtopic.php?f=107&t=6705#p96606
But the new preferred method is to use a 2 barrel to single adaptor that improves atomisation of the fuel mix
viewtopic.php?f=107&t=7294#p106051

 

[wbishop]

Thanks Ansimp! I didn't even see those threads. I did some searching but I don't think I hit all the right words. I appreciate it!

 

[joedrum]

yes the transitin piece from 1 to 2 works great works great ... but you can also cut carb body holes to to mount to type 4 ....i did ... but now use a plate on the type4 manifold ans then transition piece and grab bar runners ...but mine are 1 1/2 and no stock elbows used ... many ways to work it ...

 

[mcgovern61]

Welcome to the site from New Jersey! :clapping:

I have not done anything with single carbs yet, but these guys have done almost everything and tested all of it!

 

[wbishop]

I'm on a budget and anxious to get going on it so I think for now I'll follow your lead, Joe. Sounds like a good plan to me. I just wanna get the dang thing to start and run. Still need tires so It'll be a few weeks before I test ride, but that'll give me time to tune. I'll add pictures as I go.

 

[slabghost]

Two to one adapter centers the fuel charge from both barrels of the carb making it run smoother with a more even charge available to each cylinder.

 

[wbishop]

I managed to get my thumb into my reciprocating saw on Saturday cutting the grab bar. The blade bit into it pretty hard and shook my hand off it. Pinched me pretty good and lost some skin but it could have been a lot worse. I'm on hold till Friday or so.. I'll post an update then!

 

[wbishop]

Thanks slabghost! I'll pick one up Friday!

 

[joedrum]

i used i hand hack saw ....

 

[wbishop]

I tried that first.. bought one after my last one broke and the blade was garbage. Didn't do anything to the stainless. :-/ I'll get some better blades Friday too.

 

[krakum1967]

Take care of that hand. Waiting on my runners and manifold, got my customers carbs in the soak now that I know I fixed his electrical, I have compression, rotation, spark, and after 48 hours in krakum1967's miracle mystery sludge, we will be just fine. Well that and some time with my favorite collection of guitar strings and microbrushes. No GL, but a very pretty little GS650 will soon be making a new rider (yes he has never even rode a bike) a lot of joy. That is after Uncle Krakum's Killer Basic Riding course, and some added damage to my ol sl100 I am sure, than he needs BRC.

But I have all of the top end stuff, I just need to contact Tom, USPS crushed my filter, no hurry, I still need to figure out a linkage... uni link I guess. This one has me sort of stumped. Get better man

 

[wbishop]

Thanks Krakum! I'm halfway through my work week, but have a lot to do this weekend. I ordered the Transdapt 2025 carb adapter for Langdon's 2bbl Carter Weber carb so I can center the fuel charge, and bought a chrome headlight bucket off ebay. I'm gonna head to O'Reilly's or Napa to get my hose today, some gasket material, etc. My wife got me some mufflers for my birthday: https://www.jpcycles.com/product/4500055 I'm trying to wrap my head around mounting these. I'm not sure of the size of the exhaust as it comes off the GL1000 exhaust manifold, but it definitely doesn't fit as is. The mufflers are 1 3/4" at the inlet. I'll probably see if they've got some exhaust pipe adapters that'll work while I'm there too. The PO (my dad) Had full Vetter gear on it so I've got a bit of a wiring mess up front, and still need to figure out how to mount my front turn signals since the metal mounting tabs had to be cut to get that fairing on, but I'm getting there.

The sad part is I've never ridden this bike before, so I won't have any way to compare the single carb to the OEM 4-pack.

A couple questions for the gurus... since I'm changing my mufflers, what are the odds I might have to re-jet my carter weber carb? Has anyone had any experience with this? Also, I'm planning to get a 90 degree brass elbow for the carb, which has worked well for others here.. does anyone know off hand how big that threaded hole is? 3/8 maybe? I've read so much on these GW sites that I'm having trouble recalling what stuff works and what doesn't. Haha

I really appreciate the help!

 

[slabghost]

I'd say the odds are good you WON"T have to rejet. The new mufflers should provide enough back pressure. These motors seem very forgiving that way.

 

[canuckxxxx]

slabghost » Sat Jun 21, 2014 6:22 pm[/url]":3qhdmx65]
Two to one adapter centers the fuel charge from both barrels of the carb making it run smoother with a more even charge available to each cylinder.

+1 on the 2 to 1 adapter. I did the single carb conversion on my 82 using the same carb and manifold as you have. The bike runs pretty good but the 2 front cylinders run leaner than the back 2 as shown by spark plug colour. That is because the primary barrel of Weber end up at the back end of the manifold so are more of a straight shot to the rear cylinders. So now I have ordered the 2 to 1 adapter. So you might save yourself some time and effort to just put one in now. IMO

Brian

 

[wbishop]

Thank you guys! I'm gonna try and get it running this weekend with the carb off center. I ordered the 2 to 1 adapter and it should be here Wednesday. Really can't tell you all how thankful I am for all the help. I really really appreciate everyone sharing their wisdom! I'm anxious to hear the thing fire up!

 

[canuckxxxx]

Another benefit of the 2 to 1 is that helps atomize the fuel better. I had to go to great trouble and expense to add heat to my plenum in order to atomize fuel and eliminate bogging off idle.

I think Joe did not heat the plenum on Hooch but uses the adapter and bike runs great. Before adapter he had raw fuel collecting in his plenum and runners, when he added adapter this went away. I'm sure Joe will correct me if I'm wrong here.

Brian

 

[wbishop]

Thanks Brian, that's great news! I'm a fair weather rider since I don't have much experience, and definitely won't be riding if the temp drops below 45 or 50, so hopefully I can put off heating the manifold for a year.

 

[Dusterdude]

Shoot,ive been riding for 30 years and still wont ride under 50 if i can help it


Sent from my iPhone using Tapatalk

 

[wbishop]

Haha, don't blame ya, Duster. Gets a little chilly with the wind. I do have a question on that 2 to 1 adapter. I don't have any metal laying around that I can think of. Would anyone recommend running to Lowes to pick up some aluminum, or is there a better (cheaper) option to make the adapter plate?