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Discussion Starter #1
Hello everyone,

I'm new to the forum, thank you for allowing me to participate. I hope I am not doing anything improper with my first post here.

I'm rebuilding a VN750 - 1996. It a really nice bike.
I have a question about the VN750 surge tank and how it affects the carbs. I cleaned my carbs because I had a float valve sticking open, and I am attempting to reinstall them, but I can't (so far) to get the surge tank hoses connected back to the carbs.

So, before going ahead and connecting the surge hoses, I tried starting the bike without them in place, just to see if the carbs were okay. I found it will not start without starting fluid. Then it starts, but will only keep running at high rpms and it also backfires. It runs really bad.

I welcome any comment or suggestions.

Thanks,
Ray H.
 

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The Professor
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3,147 Posts
Hello everyone,

I'm new to the forum, thank you for allowing me to participate. I hope I am not doing anything improper with my first post here.

I'm rebuilding a VN750 - 1996. It a really nice bike.
I have a question about the VN750 surge tank and how it affects the carbs. I cleaned my carbs because I had a float valve sticking open, and I am attempting to reinstall them, but I can't (so far) to get the surge tank hoses connected back to the carbs.

So, before going ahead and connecting the surge hoses, I tried starting the bike without them in place, just to see if the carbs were okay. I found it will not start without starting fluid. Then it starts, but will only keep running at high rpms and it also backfires. It runs really bad.

Thanks,
Ray H.

Those boots are a PITA! make sure you have the corrcet one for carb, they are marked F and R. It sounds like you have more problems than a stuck float. If the carbs sat with old gas your enrichment circuit and idle/pilot jets are probably clogged. You may need to completely dissasemble the carbs and soak them in carburetor parts cleaner. You can get at any autoparts store. it is in a gollon can and it has a basket for small parts. Put all the small part in the basket sepaerating the front and rear parts. Put the main body in the bottom and let soak for 2-3 days. Make sure the jets are clear before you install them. :smiley_th
 

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Kawika
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I used some silicone spray lube on the boots and it helps to let parts "slide" by when pushing the carbs in...wipe off the excess when finished. It also helps on the hoses from the carb intakes to the airbox....mine popped right in after lubing it.
good luck and welcome to the forum!:beerchug:
 

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Discussion Starter #4
Thanks to Lance and Dave for the advice..... Yesterday, I was able to get the bike running better. I adjusted the carbs a little leaner than it was before I cleaned them. I also sprayed some WD40 in the throats while it was running. It seemed to help.

I'll have to try the silicone spray lube on the boots. It will be getting on those hose clamps on the boots and tightening them..... that will be the next problem to tackle.

I'll leave this carb on now that it's running better. I have another carb for this bike that I will take my time and rebuild per the advice from Lance. I really appreciate the help gentlemen.

Thank you,
Ray H.
 

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The Professor
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Have you made any more progress? Let us know. :beerchug:
 

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Linkmeister Supreme
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I don`t have any further tech advice for you, but welcome the forum Ray.
 

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Discussion Starter #9
Okay, guys...I have ridden the bike some 3 or 4 miles since last post. It needed to choke full to run well.???? got the fuel /air mixture screws open 3 turns..

Also, I noticed sometime unusual.... if I put my three fingers partially spread over the throat of the carbs (no boot to the surge tank on yet) I get totally different effects. Whith the front carb it speeds up the bike (accererates), but the same 3 fingers over the rear carb intake..... chokes it down? I checked all hoses...and fuel from the tank to both carbs...it check okay.

Anyone have any ideas why?
 

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My guess is that having the boots off really messes up the air intake and will allow 'nasty stuff' in your carbs and also a poor running condition...
 

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Old Truck Junkie
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The problem is with the front carb. I am not sure what the problem is, but I think that is where the trouble is.
 

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Discussion Starter #12
you may be right.

I'm sure you are right about the nasty stuff getting into the intakes with the surge boots off, but as I said, I only road it 3 or 4 miles and it was running bad,from the start, unless the choke was on full.

Meanwhiile I'm rebuilding another set of carbs, they're about done except, for new air intake valves. I'm waiting on those to be shipped to me.

Guess, I'll put on the rebuilt set...when I'm done and open these up again. I figure it's time for new plugs and plug wires also..the spark is not real strong.

I'll eventually get it right...

I've got another running VN750 with bad forks. I'm thinking about taking The engine out of the frame and using that engine to test carbs that I work on.

I'll fix it so the carbs will be easy in and easy out, without all that frame in the way. I don't mind tinkering with carbs ...it's the removal and re-installing then that I don't like dealing with.

Thanks, for the comments gentlemen, I need all the help I can get.


Ray
 

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The Professor
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I'm sure you are right about the nasty stuff getting into the intakes with the surge boots off, but as I said, I only road it 3 or 4 miles and it was running bad,from the start, unless the choke was on full.

Meanwhiile I'm rebuilding another set of carbs, they're about done except, for new air intake valves. I'm waiting on those to be shipped to me.

Guess, I'll put on the rebuilt set...when I'm done and open these up again. I figure it's time for new plugs and plug wires also..the spark is not real strong.

I'll eventually get it right...

I've got another running VN750 with bad forks. I'm thinking about taking The engine out of the frame and using that engine to test carbs that I work on.

I'll fix it so the carbs will be easy in and easy out, without all that frame in the way. I don't mind tinkering with carbs ...it's the removal and re-installing then that I don't like dealing with.

Thanks, for the comments gentlemen, I need all the help I can get.


Ray

With the boots off of the carbs it will run like crap, it causes a severe lean condition. You must have the boots on, with the choke on it dumps in more fuel. :smiley_th
 

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Linkmeister Supreme
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With the boots off of the carbs it will run like crap, it causes a severe lean condition. You must have the boots on, with the choke on it dumps in more fuel. :smiley_th

This is a little off topic, but related. When I was reading this, a light came on in my head. This lean condition must be the same reason that the old side valve Briggs and Stratton lawn mower engine, would never start without the foam air filter on and the holddown screw in place. Would that be right lance?
 

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The Professor
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This is a little off topic, but related. When I was reading this, a light came on in my head. This lean condition must be the same reason that the old side valve Briggs and Stratton lawn mower engine, would never start without the foam air filter on and the holddown screw in place. Would that be right lance?
That would be right. :beerchug:
 

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Linkmeister Supreme
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Simple Solutions
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with the boots off you said that the choke has to be all the way on and when u put 3 fingers over the throat one would accellerate and the other would run like crap.... i know when mine was runnin like crap i could pull my wires off the bad hole and no change... are u sure u are running on both cylinders???
 

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Discussion Starter #18
I've ordered new plug wires, and I'm buying new plugs today. What plugs do you recommend? Also, this morning I tried to find any leaks in the vacuum hoses and the boots to the engine with some starting fluid (with cyl. lub.) around the boots and hoses...but... I concerned that the overspray kept getting into the intake throats and speeding up the engine, so I couldn't tell for sure.

I'm going to do a complete electrical tune up, and then sync then carbs with the top boots on.

I'll keep you all informed....thanks for the help....I'm learning as I go. I really appreciate all of you for your input.

Ray
 

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The Professor
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I've ordered new plug wires, and I'm buying new plugs today. What plugs do you recommend? Also, this morning I tried to find any leaks in the vacuum hoses and the boots to the engine with some starting fluid (with cyl. lub.) around the boots and hoses...but... I concerned that the overspray kept getting into the intake throats and speeding up the engine, so I couldn't tell for sure.

I'm going to do a complete electrical tune up, and then sync then carbs with the top boots on.

I'll keep you all informed....thanks for the help....I'm learning as I go. I really appreciate all of you for your input.

Ray

The plugs you want are NGK DPR7EIX-9 Irridium Plugs. :smiley_th
 
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