rjsteiner01

There are some NOS intakes available on eBay for the $145 I think I saw last two weeks.

Winter time in Eastern Oklahoma so I took some time to dismantle the carbs and here is what I found: All jets clear on #4 cylinder, Pilot jet is a #17.5 & main jet is a #95. This looks stock to me (not jetted). I blew out all ports and passages, not sure if that idle passage is clear because when I apply air to where the idle screw goes (screw is removed) and hold my finger over the small hole that enters the carb throat, I don't think air goes any where, hard to tell. Might have to put them in a pulse tank to clean them up. I found the plastic stop on the jet needle to be on the last position towards the pointy end(notch #5), is this correct? Any one know what setting it is supposed to be set at on the Gen 1.5, 28mm carbs? Another big find is a very loose almost noncontact connection on the white wire for the #4 coil!!! It turns out the PO wanted to hook his tachometer to the # 4 coil, he added some of those two on one spade connectors to the white and red coil wires. Can this tachometer interfere with the coil signal?? Is there any info on the 28mm carbs on how they work (circuitry)? I think I'm getting some where on solving this long thread.

Goose, I have not removed the carbs yet on the bike but have made this observation: Along with a cold cylinder temp on the #4, I can turn the idle mixture screw and it makes no difference to rpm, I did check to see if fuel was getting to carb by opening fuel drain on the bowl, it is getting plenty of fuel. I also have spark for that cylinder.

Ok folks wanted to get back with some test results/findings with my bike performance problem. (popping, low compression and poor fuel mileage). Purchased a Milton leak down tester and finally had some time and a nice day to perform the test, tested all four cylinders and all passed with flying colors! Found # 3 exhaust manifold pipe loose ( I have checked this in the past and found them tight) This time I did have a loose bolt. I now have no popping in the right bank. Found that #4 cylinder must not be getting fuel because after 15 minutes of running the exhaust pipe never got warmer than 100 degrees, all other pipes very hot. I checked the spark and have it, I let the bike run on the spark tester for about 5 minutes and found no intermittent spark...it was steady. #4 cylinder was still cool to the touch. I tapped on the side of the carp thinking I could free a stuck float but no results. I turned in on the idle mixture screw as Goose suggested with no results. All other carbs responded immediately. Good news, no head removal. Carb removal is next, I'm only running on three cylinders. That will affect the MPGs!

OK, checked on the leak down test tools and watch some vids on how it's don. I think I can go with the Harbor Freight based on the expense and how often I will use it. What is the problem with the Harbor Freight tool Goose? Any how, didn't have a lot of time to mess with the bike but I was given a laser thermometer this weekend and figured I would try measuring the exhaust ports to see how it would work. Cranked up the bike and it run rougher than normal (40 deg out). I also don't recall it popping the first few moments after start up. Had to use full choke for about two min. After pushing in in the choke, bike would not run without a little throttle, I up the throttle stop and it ran for a min or two between 900-1400, it was not a steady rpm. Then rpms got steady and climbed to 2k+, had to move the throttle stop back down! Thought to myself one of the cylinders was not doing it's fair share of the work! Don't know if it's fuel, spark or compression. Long story short, took temps of the cylinder exhaust ports (above where the pipes flanges mate up). By now the bike was warmed up and I had that nasty occasional pop on the right bank. Readings are as follows: #1 300, #2 198, #3 254 & #4 177. I will be doing a leak down test next, seems simple and I can see if I have a mechanical problem right off.

Goose, That is the most detailed description I have read on setting the idle mixture screws, I will try it! As for the rest let me try to answer: The bike was hot when I did the compression test. All plugs were removed and hot to handle! (used gloves) The air filter WAS NOT removed. Battery was fully charged. I did have 160-165 on the right front cylinder while all other readings were 180-185 (this is the cylinder that sounds like it "sneezes" in the exhaust manifold every so often when at an easy cruising speed (3rd-30 mph) steady throttle) Sticky valve? I'm with you on the fuel cleaners, they only work on a somewhat restricted passage. I removed the carbs from the bike and went through all of the and could not any thing wrong, float were set good, jest clean ect. I did not record jet #s and wish I did just to see if they were stock or re-jetted. I did not remove the intake manifolds and check the orings. When I reinstalled the carbs I did put the vent lines in the correct location (they were facing forward before). What is all involved in the leak down test? Special tool? I will try adjusting the idle mixture screws 3.5 turns and see if I get the effect while turning in and out this weekend and let you know how that went. I also at one time plugged all holes that were drilled into the pipes (pipe plug and exhaust dope). No improvement in popping. In the next week or so I will be removing the carbs and going through all wiring looking for the obvious. Goose, I appreciate the in-depth response and let you know how it goes this weekend.

I checked the manual (Yamaha manual P/N LIT-11616-10-67) and normal compression is 216 psi & minimum is 185 psi with a maximum difference of 14 PSI between high and low reading.

Thanks for the advice, I do need to get some carbon remover to clean the combustion chambers. Compression was in the 180s ( I would have thought that would be good, Specs say it should be 240 psi I think). I'm not making oil and that's a good thing (fuel dumping in cylinder). I was also thinking a stuck valve or maybe an intermittent ignition problem, maybe the plug isn't firing every time it should. Anyway, I appreciate all the good feedback.

Yes did a wet test with WOT, compression improved by about 5 psi (not much higher) that's what made me think about the valves. thanks.

Thanks for the info on pulling the heads in the frame, nice to know it can be done. Don't want to do it if I can help it, but glad the hear I don't have to remove the engine to do so. I have not checked the valve clearance. I have low compression on all four cylinders, let me ask this... if the clearance of these valves are changed with shims and the engines wears with use, would the valve clearance not increase with mileage? Thus the valves would stay closed longer? If the valves are closed they would hold compression (unless held open by carbon or burnt). If I understand the valve clearance adjustment method on these engines correctly, we would always add shims to make up for the wear? I was thinking that maybe this bike was run lean (K&N filter and drilled exhaust pipes) leading to toasty valves, thus low compressions. GeorgeS, the bike has 21K for miles. I will respond to your PM shortly. I will point out two things I noticed as of the last few times I had it out: Started it one cold morning (46-48 F) and the bike did less popping. When ever I throttle up (in 4th) going down the road, the bike chatters/is not smooth, like the clutch slipping or I'm dumping fuel into a cylinder that's not burning properly. I appreciate the response, this is such a good looking bike and the PO put a lot of $ into the extras. I would just like to get the MPGs back and get rid of the popping. Again, thanks for support and look forward to the response.

Hi All, I have a 1998 RSTD and have low compression. I did the compression checks and it looks like I have burnt or high carbon loaded cylinders. I also suspect that I have a sticky valve. I will take the bike down for its winter nap soon and wanted to know if I have to remove the engine for head removal or can it be done in the frame? I have other work I will be doing (tires, coolant & carb work). Thanks in advance for your input

What's a colortune?

I have 1997 TD with 28mm carbs and was not aware that the jets were different from one carb to the next, I will consult my manual for jet size and location. Previous owner may have re-jetted as you pointed out and made things worse. I was in the carbs inspecting but did not record jet #s . Float levels were all the same and I was only having fowling on right side. I could not find any info on how to set those idle screws, I guess you have to have a co analyzer to do it correctly. I'm sure I do have a carbon deposit problem as you describe (based on plugs & muffler drain hole deposits on my carport floor upon start up), what's a good way of dealing with it other than head removal? I have sync'd carbs and turned in on idle screws for # 3 and 4, I will run a few tanks through and check plug condition and let you know. many thanks for your input.

I did have to make a bunch of turns to get them sync'd, no holes in diaphragms, no obstructions in jets, I will get some sea foam as it couldn't hurt. I did the sync last weekend and haven't really had it on the road to see the improvement in mpg, will let you know. Thanks for the input, how do you do a simple reply without the quote??

Hello folks, I'm new to the site and have enjoyed the various threads. I have read up on exhaust popping but I think I have an other than "lean" condition. I will try not to be long winded but want to give those out there all the info I have on the symptoms/condition. Bought the bike with 21K miles. I get about 25 miles to the gal Popping from both sides but mostly from the right at idle and deceleration. Compression check, bike at normal temp/then added a little oil, #1-185/190, #2-180/180, #3-180/185, #4-160/165 Bike fowled out #3 & 4 plugs after putting a few hundred miles on it and I had to limp back to the house, new plugs and ran great. Bike has K & N air intake, drilled exhaust pipes Inspected carbs and floats/jets. Found idle mixture screws out collectively 3.5 on the left and 12.75 on the right! I turned all to 1.5 from seated and synced the carbs, got rid of a lot of the popping but still fowling out right side #3 & 4. Turned in right side to .75 open and after two tanks of gas the plugs look like they are burning correctly and I further reduced the popping but I still have it on the right side only @ idle. If I am cursing in 4th without loading the bike I hear a ping in the right front cylinder every so often like improper ignition timing (I checked timing @ idle and it was with in the little window) Seems like a valve sticking open or maybe burnt? My compression is low in accordance with the manual, is this due to burnt or sticky exhaust valves? I would think that this bike should not be worn out (ring/cylinder) @ 21K miles Can I get away with operating it until a winter dismantle? Could a K & N filter and drilled pipes caused a lean condition? Looking forward to your input.