Hey fellas, Well, the issue I'm having right now is after starting it, it will not rev past 6000 rpm, and struggles to pass 3000 rpm (but usually does). If I pour on the throttle it will die down or stall, if I slowly roll it on it will do as described above. It seems to do it from first being cold and even when it's warm, but eventually (after trying to rev it for a while) I can get it to go past 6000 rpm and when it does it will usually do so again and again, slowly doing so more freely. Choke works correctly and the bike starts very easily, even when cold. It's that bad sometimes that I can no longer go up my street and have to go down, partially rolling it down and and going through the gears up to about 5000 rpm then dump it in 1st or 2nd to force the rpm's up, after doing this it starts to clear up, but if the bike is turned off then re-started while warm, it's fine, if it's left to go completely cold, it starts all over again. I wait till it's warm to take off too by the way. I had an issue where I had no top end power which turned out to be the slide holders not sitting correctly, after taking them out and putting them back in, I have that power back but this issue started. Carbs are balanced and I have leaned out/richened the idle mixture screws to no avail. Fuel can usually be smelt after starting from cold too. I'm thinking it could be a vacuum problem or could somehow be too rich? Any ideas?
Just a shot in the dark...but have u checked the carb rubber manifold boots? If they are cracked thru and brittle they can cause vacuum issues....and they need to be squeezed "open" to see any degradation. For anyone who doesnt get what I mean by "open"
Ta mate, I'll be sure to check when I take the carbs off. It was fine until I moved the slide holders out of the notch, was the only way I could get full power back in the higher rpms, but straight after that is when this issue came about, could be a fluke and something else went wrong/broke at the same time or could be related, not sure.
Hey Shimmy Understand your frustration, shouldn't be this hard. Think Greyimport is on the money, as wear and tear on the rubbers on most carbs deteriorates after a certain time. When this occurs your fuel to air ratio is all over the joint and hence poor acceleration and at times very poor performance, if any!! Currently I am encountering similar problems with my GSF400 Bandit. Prowling the net to find parts and hopefully some answers, sites in the UK and The US have highlighted problems associated with carbs and often with seals, rubbers, hose and so on. Lucky for me that during my search have found other models that have the same carbs and so am able to source parts from Suzuki direct. When you get the carbs off, double check gaskets, seals and hoses and have a good look at the diaphragms as these can be the main culprit. Hope you get it sorted mate.
Ta mate. Diaphragms are good, checked them a couple of days ago. Yeah, I wouldnt be surprised if it is something that's deteriorated, it is 22 years old after all. The only thing that keeps me thinking about it is that once it clears up, the bike runs really nicely, from idle at about 1700rpm all the way to 17,000rpm+. I'll still check though, I'll try and get a video in the morning to show what it does, and might get the carbs off right away (kinda need the bike going tomorrow night, lol).
Sooooo... I finally got around to doing that video... For a couple of days after my last post the issue was almost non-existent, then came back. I'm going to move the throttle slide holders again (put them back into the little notch), as that was when I first started noticing it, just if I do it, my top end is gone.
Hows it going with this problem? Have u checked the spark on each cylinder? ...... is the charging system working at its full potential?
I put the needles onto #2, which improved it considerably, can now go up my street when first leaving. Nothing wrong with the spark or battery (have a voltage/clock thing on the dash). The issue is still there though, and you can smell fuel for a short while after first starting it. Once it's ran for a while a though (as in moving, sitting stationary, it doesn't really go away) it's perfectly fine, smooth all the way up. It will usually start quite easily when cold, with full choke. It almost seems as though it's flooding or somthing but I don't really understand how it could, as the fuel pump is off and it's gotta get back to stone cold before it does it again.
Hey Shimmy I'm going to throw my 2 cents worth in, the Across runs an electric fuel pump due to the location of the fuel tank. Could this excess fuel be from the carburetor floats being slightly ill adjusted, if they are the excess fuel has to go somewhere. Perhaps worth a look. If the floats measure up, then we have to look elsewhere.
Hey Phil, I'd say that could be a very real possibility. I don't think its an air/vacuum leak of some sort because it only does it when it's stone cold. Are the floats adjustable or could it be something causing them friction? I did run a fuel additive a while back, which was supposed to help clean out the carbs/valves etc, just occurred to me that it could have moved some gunk to the floats? The only thing I don't understand if it is this though, is how is the fuel getting into the carbs if the fuel pump is not running?
Yes and yes ...... The carbys havnt been stripped down? http://www.oocities.org/ozcross250/holder.html Float height down the page a bit...... http://www.oocities.org/ozcross250/needles.html
Thanks for that mate. I have not pulled the carbies down yet, been meaning to but just havn't. According to that, I should raise the float level? But whats up with being able to smell a bit of fuel at first, or could it just be inefficient burn/too cold a plug? Or, it probably doesn't need adjusting but rather just a decent clean? Could have been the additive that created this problem?
Im no expert on additives but there would be nothing that beats physically pulling down the carbs and doing an overhaul...as u mentioned before, we are dealing with old bikes with dubious backgrounds......not neccesarily pulling them apart into singles but doing a major clean and replacing rubbers etc. , a bit of lube on the outside workings. You may be surprised what crap u find in the bowl. I would initially (after the clean) set your floats to the default setting and go from there. You may find this will solve all your problems in 1 go. Here are bowls from my spare carbys.......
Cool, yeah I'll get around to cleaning them soon enough (wish I had a shed to work in). I've already ran the additive, I just mentioned it, as it may have just dislodged some gunk that was in an area that was no effecting it. Anything in particular to use to clean them?
I use acetone but not on plastic and a throw away brush. blow with compressed air. to keep clean wipe with wd40. keep in plastic sandwich bag. carb cleaner can be acetone or methanol.
Hey Shimmy I use Nulon throttle body cleaner, seems to work pretty well. We spoke about the potential problem with your floats, however leaks can eminate from damaged and worn needle and seats. Check the status of the needle, should the tip show signs of wear it would wise to replace them. The needle is attached to your float, as fuel enters the bowl the float rises and eventually pushes the needle shut within the seat, thereby shutting off the fuel supply. As fuel is burnt away the float drops and fuel re-enters and so the cycle goes. The needle thus works constantly keeping fuel flowing to the carb, wear and tear can and does occur. As GreyImport and risky have mentioned, getting the carbs clean is vital to a smooth running engine, hope these tips help in getting your issue resolved. Good luck mate, as always keep us posted if you need any further assistance. Cheers Phil
Thanks fellas. I think we all agree that I need to get off my arse and get those carbs off eh, lol. I might give it a go next week.
