No/slow acceleration. No top end.
 

Hey all. First, Thanks for the wealth of knowledge and support already on these forums and all the contributors. I have spent hours pouring over all kinds of topics on this site which were informative, helpful, and also gracious when user error was discovered.

Secondly, on to the problem at hand. I have had my GZ for 2 years. It ran for most of 1. Finances always being very limited, it sat for about a year with little progress made. I ended up having to replace my crankcase due to other problems and now all is reassembled. Those issues have been resolved leaving a newly discovered one. I have no top end power at all. Timing is dead on; I followed the maintenance procedure to the letter when reassembling everything. I have adjusted valves back to spec. They were horrendously tight and not sealing. No gap at all. Intake has been set to .008 and exhaust to .012. Piston was at TDC on compression stroke. Many thanks to the great instructions found in other threads for this. I did a compression test which yielded 180 peak psi which is solidly within normal operating range (140-199) though I will test again as I don't think it was quite warmed up enough.

It will crank right up with a little choke and seems to handle throttle just fine in neutral. It does not want to run without choke but can be coaxed along slowly, but starts running badly or at least inconsistently and may or may not cut off. If I turn the idle adjustment to increase the idle as far as it will turn, it will run with no choke at all without cutting off, but badly (roughly the same as it is with half choke and normal idle speed).

Out of neutral it will pull with no throttle to maybe 1/4 throttle but pretty weakly. It does better with more choke. It will pull a tad harder, but still will not increase past 1/4 throttle. If I give it more throttle than that it will start sputtering and lose torque, and when throttle is released it will backfire, pick back up slightly and resume running at no throttle to 1/4. It does this in first and second gear. It will not take any throttle at all in 3rd or above, and will not pull at all in 3rd or above. I cannot maintain 25 mph in 3rd on mostly flat ground.

To me this sounds like fuel delivery problems. The tank sat with very little gas for a very long time. Bad gas was purged and replaced with new gas and seafoam (3 oz. or so). There was a good deal of crud in the tank, petcock, fuel line and carb when I first tried to start it after reassembly. Petcock was removed and cleaned. Fuel line was likewise. Carb was pulled, opened up, and cleaned to the best of my current ability. No inline filter yet but working on it. I thought that I cleaned it pretty well when I had it off before, but it may need more thorough work beyond my current skill set.

Thoughts, comments, observations, suggestions, pointing and laughing (as long as it includes the previous as well) are all welcome.

http://vgrhq.com/wp-content/uploads/...nglaughing.png

But in all seriousness - let me just ask a few questions for clarification.
Can you rev the bike up just fine in neutral? Can you, at any point, get the bike to idle properly in neutral without using choke?

If the bike won't run without choke then there is an issue in the carb and/or in the choke circuit. If you know what you're doing, I'm going to suggest just pulling it again and cleaning everything, one step at a time. I feel like there's just a blockage somewhere in there.

To check the petcock for debris, pull the fuel line and see how it flows in PRI. I think if that flows smoothly then don't worry about the petcock. Do the same similar tests for each system, making sure it operates as it should off the bike, before buttoning everything back up.

It SEEMS to rev pretty well in neutral. Better immediately after startup than after it has run for a little. After warm up it starts popping pretty good when you let off the throttle in neutral. It will idle in neutral fine without choke as long as the idle speed is in the proper range. Too low and it starts wanting to cut out as I understand is normal. Out of neutral it will still idle just fine at first, but after it warms up it doesn't idle as well. Adding choke seems to let it idle better after this happens.

Flow at the petcock after cleaning is just fine. But the first couple times I ran it, a check of the fuel line did find some flakes of crud. Less, the more it has run. This was before I removed and cleaned the carb. I did initially find blockage in one of the jets and cleaned it out. Its definitely possible that the seafoam knocked some stuff loose and blocked it again, but since it seemed to rev ok in neutral, I wanted to get other opinions for things I may have missed. I try to be thorough, but by no means am I perfect.

Ok - Flush the tank again. Sitting for so long you have no idea what's floating around in there.

This all just feels like a fluid flow problem - in the tank, in the lines, and in the carb itself.
A good cleaning doesn't do you any good if it immediately gets clogged back up with junk.

Popping can be fuel delivery, but it can also be a lean mixture - it's what happens when people decelerate after having holes punched in the exhaust, for example. Ensure that there are no vacuum leaks and that the headers are sealed going into the head.

I've used a smoking incense stick to search for leaks before with good results. Get the tip into proper ember form and get your bike into a garage, or anything that blocks wind, if you can.

Any other opinions, comments, concerns? This sound about right to everyone? I'd like to hear thoughts from one or two more people before I take the carb back off, though I also think/hope its just the carb. Thanks

You can trust Jonathan. His experience and judgement is of great value to all of us. :tup:

I agree with Water Warrior 2. Jonathan has been around a long time and has helped many on this site. After reading your thread, I would say Jonathan is spot on. I have followed his suggestions in the past and have had all positive results from them. Hope this helps.

Cool beans. I will pull the carb again today when I get off work and give it a good soak in cleaner. There are no vacuum leaks. That was one of the first things I checked. My exhaust is factory, no auxiliary holes added. Headers are sealed good and tight. A little popping I'm used to, as the bike did a little of that before, when it was running well. My main concern there is the sputtering and coughing when you apply throttle immediately followed by the popping and better running when you let off the throttle. I'll also take the opportunity now while the carb is off to find and install an in line fuel filter. Thanks guys. I'll keep you posted. Thoughts, comments, etc. still welcome.

If it doesn't already have one install an inline fuel filter after you clean the carb and tank.


:)

Check the pilot screw on the carb (unless it's sealed). It adjusts the fuel mixture. Maybe when you took the carb apart, you changed its position.

Pilot screw is sealed. I may play with that later on, but not until I get it running reliably in the factory setting. Thanks though.

Update: Rained pretty hard down here the last several days, but yesterday I was able to remove the carb again, disassemble, and soak everything. Yes, it was indeed filthy all over again. All hoses, jets, etc. cleaned out. Did the needle shim mod while I was in there again. Tomorrow will drain the gas tank, clean the petcock again, because holy crap at the garbage still coming out. It would pull gas through, but with the hose disconnected and some gas in the tank on prime I was only getting a steady trickle instead of flow. I will also install an in line fuel filter tomorrow.

Now question: do ya'll think its safe to scrub the inside of the tank to get the rest of that garbage out, and what kind of cleaner do you think would be safe to use that would flush out without adverse effects on the gas once its filled up again? Thanks guys!

It should be fairly easy to remove most of the loose stuff in the tank. What "I" would try is draining the tank, add a cup full of clean gas and a wash cloth. Remove tank from bike and just keep twisting and turning the tank to let the wash cloth do its job. There may be a chance of damaging the in-tank filter but you will have the inline filter working for you later on after it is all buttoned up
Do the swish and wash cloth a couple times or until there is little to none mung and particles showing up when you drain the cup full of gas out of the tank.
Yeah this is a messy and slightly dangerous idea(playing with gas)but it may work.
After all that................there will surely be a better idea soon from some one else. And hopefully safer too.

My 91 year old friend, who rode motorcycles from his teenage years until he turned 87 years old, says Marvel mystery oil or WD-40 inside the tank will remove crap and rust. Plus alot safer.

Marvel Mystery Oil is decent stuff.....when I used to collect and enjoy Hudsons....I would use 4 oz. of MMO with every fill up. (that was a 20 gallon fill up) Never a problem.
And back in the day, MMO made an inverted oiler that also feed some into the crank case to mix with the oil and everyone of those so equipped, sounded and felt so extra smooth.

WW is guiding you right - and anyone who is a friend of MMO is a friend of mine.

Drain the tank - That gas sludge is just no good. Do whatever you have to do - just pour as much of that crap out of the tank as possible. Your goal is not a pristine tank inner surface, but at least one that isn't flaking and sending varnish deep into the carb.

If you can find one, buy or create a new petcock gasket and remove the petcock as well to do the job right.

Drain any fluid that is in there and then pick your poison as far as flushing the tank. Gasoline and a washcloth will do a lot of good. You can also mix up a solution of kerosene and any carb cleaner that you like. (With the kerosene solution, keep the petcock on, seal the gas cap, and shake your tank like a giant gear-head martini mixer. Then pop both openings, drain and repeat until what comes out is pretty clean.

Kerosene isn't nearly as explosive as gasoline, yet after you're all done, the kerosene that is left in the tank won't damage in any way your new tank of gas and you won't have to worry about the two not being compatible.

I've also used a pressure washer on old tanks with good results. Again, it's better with two openings, one for an inlet and one for an outlet. Don't use full pressure or keep the stream in one place the whole time.

Anyway - your goal is just to remove the gunk and then get new gas into the tank as soon as possible to keep any more surface gunk from building up.

And then, going forward, use 1oz of Marvel Mystery Oil in every tank to start building up a thin coating of oil to stop whatever metal breakdown is happening inside your tank.

The inline fuel filter is a must on this bike and will help keep your new carb as clean as you are about to get it.


You can do this, man. It's no big thing. You're only a couple of hours away from a running bike again.

Keep up the good work.

Thanks for the helpful advice guys. It is very much appreciated. I'll try the rag solution first as I have all that on hand. I've also got a brush used to remove excess dirt/lint from the lint trap for a dryer that I plan to use to get some of the less accessible places in the tank. Its bendy and has lots of reach, plus it's nylon so it shouldn't hurt anything and it's good for that kind of stuff. Petcock is gonna have to be removed again regardless, because all the garbage in the carb is obviously in it too. Hope to be riding again this weekend. It will by my first independent transportation in almost a year... O_o

Even better! Freedom and Independence is a very empowering thing.

Holy crap that was trashed. Ok, update. Petcock is apart and soaking. It was almost completely clogged with crap. One of the top filters is off completely. Gonna have to fish that out of the tank here shortly and see what the story is there. That is the cause of the carb being completely choked off it would seem. Fuel filter is purchased and waiting. Back with good news soon I hope.

Many are not aware of the filters in the petcock. A friend around the corner from me kept complaining about his carb. needing cleaned and how he must be doing something wrong because the bike still was not running right. I told him to install in line filter to pick up the crap before it got to carb. During the conversation he mentioned that it seemed as if the carb. was starving for fuel. I asked if he had checked the filters in the petcock. He swore there were none. I bet him $20.00 there was. One hour passed and he came down with $20.00 in his hand and thanked me. He said he was ready to give up and was going to take it to a shop to have the carb. adjusted. After cleaning the filters in the petcock, the bike runs like new. I told him to keep the $20.00 and buy the in line filter to keep him and the carb. happy.

Ok, so I ran out of daylight. Tank is as clean as its going to get for now. Petcock is assembled and clean (with the missing filter found, cleaned, and reattached). Carb is sqeaky clean. Inline fuel filter and new fuel hose ready to go. Now just have to put it all back together and fill up, which is my plan for in the morning. We shall see :)

Will keep my fingers crossed while waiting for your update. Good luck.

Ok, I've after 30 miles here is where we're at. Fuel filter is installed (will be replaced soon because it is a paper filter and doesn't flow freely enough to feed the engine on run, but does fine on prime for now). Engine runs fine without choke. Revs up all the way through to full throttle. Still experiencing power loss at half throttle and above in all gears, but with worse effects in 3 and up. Torque seems really weak in first to start, but picks up just fine when it reaches about 5mph and will go to the top of the gear. Second gear will go all the way to the top of the gear as long as I do it slowly. I have to be at the top of two to go into three or else it drops down to about 20mph. I can accelerate VERY slowly to near the top of 3rd on flat or slight incline. I can reach the top in decline at about 35-40 mph but again, at half throttle it will start reving up high and I begin to decelerate. 4th and 5th are essentially not of functional use at the moment. I can maintain 40mph in 4th at the very bottom of the gear on flat ground or decline only and cannot accelerate at all beyond this point despite the engine revving up nicely. Any clues or suggestions at this point? Its doing significantly better now than it was, but it would be great to have it running at full strength... Thanks for all the help guys!

We need to get it running off prime. Air box, drain hose and air cleaner clean? Idle reset after warm up to proper specs.? Spark plug fouling out? Change fuel filter. Need to get proper fuel flow thru it to carb. I would start with the fuel filter!

Spark plug is great, airbox, drain hose, air cleaner all clean. It runs fine off of prime, but it pulls the gas from the carb slightly faster than it pulls gas through the filter, so it will start to starve. Its off prime when its not running. The only filters available around here are for systems with fuel pumps. Idles great.

Check lawn mower shops for filter. Alot of lawn equipment have filters that would work. most of the lawn equipment do not have fuel pumps.

Already checked. Not many places around here that sell stuff to do work yourself. The small engine shops around here just do the work and wont sell you parts. Had to go to the big box stores to find this one. I'll use it until I get one online.

I will do some brainstorming tonight. I think you are close to having it fixed. Wish you could change the fuel filter. If tank and petcock are clean, you could take out fuel filter just to see if it changes anything. just need a little gas line.

Go to Home Depot. They sell small engine parts and you can pick up a Briggs and Straton fuel filter.

Edit: Link to fuel filter on Ebay.

http://www.ebay.com/itm/6-UNIVERSAL-...item51c0710d2a

:)

Mole, that is the exact filter I have installed. It is not letting enough fuel through fast enough to keep the motor fed.

Clutch. Cable. Play.

Update! Thinking it might be my clutch slipping, I was reading through some other threads on here when I realized I had moved my clutch cable at the handlebar while checking other things with my bike. I went outside to check if I had put it back. I hadn't. Now its adjusted properly and runs great!!! Thank you guys for all your help. Also, after a day, the filter is letting gas though just fine on run, where it was slow before. Now I just have to fix an oil leak at the valve inspection caps and she'll be better than when I got her :D

I was wondering about that cable last night. Glad you found the problem. Have fun riding the GZ.

This one looks similar to the Briggs and Straton fuel filter. These small engines do not have a fuel pump so unless that filter clogged up fast it should work. Also, take the fuel switch out of PRI. It can cause fuel to leak down into the engine if your needle should not seal perfectly causing all sorts of problems.


http://www.ebay.com/itm/Visu-In-Line...37425e&vxp=mtr


:)

New problem. On a decent trip of about 35 miles to register for classes this fall, my clutch lever begins to ease back to the handlebar over about a minute give or take, then I have no clutch. I had to finish the trip with zero clutch which I can tell you got pretty crazy. Ideas? Seems like it might be the cluch push piece has worked its way unscrewed, but this should NOT happen right? I remember there being a lock nut which had to be tightened (which I did). Should I have used loctite in there? Too late to open her up today so for now it is a mystery which will likely have to wait until this weekend...

So I just went out and did it last night anyway. The lock nut had come off completely, but I found it with little effort. Cleaned it up along with the adjuster screw and loctite on both. Problem solved. Again.

It's amazing what problems little things like a lock nut can create - You'll be rollin' worry-free now.

This was a very helpfull thread by all of you. Glad youre up and rolling again.