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      JUST IN!   04/24/2018

      HOW TO: 4-STROKE PISTON REPLACEMENT DONE RIGHT!

Hollow Point

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About Hollow Point

  • Rank
    TT Newbie

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  • Location
    Washington
  • Interests
    Snowmobiling, Hunting, Fishing,
  1. In reading the TTR-225 posts I see it's pretty darn common for people to experience top end carburetion problems (missing, popping, etc. Even over on the XT-225 site guys are seeing the same problems. Most posts seem to say the problem seems to magically appear one day. I too have this persistent problem and have changed the plug (which seemed to help), checked the in tank fuel filters (which were clean), drained and put in fresh gas (didn't seem to help), bumped the main jet from 130 to 135 (didn't help), I now have a 42.5 pilot jet to install but that shouldn't affect the top end much if at all but it might help the hard starting issues, I have opened up the airbox, even ran it with the door off (seems to make it worse), I shot carb cleaner on the carb boots while the engine was running to find any air leaks (found none), I even ran it with the carb boot between the carb and the airbox removed and it still does it. The one thing I have tried to do with no luck is to raise the needle on the carb. Unfortunately, there is only one slot in the carb for the clip. My question is, is there a carb needle of the same length and taper that has the adjustably of multiple clip positions? I'm convinced this has to be at least part of the answer to the upper mid to top end RPM problems. I know the needle is a mid range adjustment system but the lack of fuel in the upper mid range can bleed over into the lower top end where most of us seem to be having our problems. Does anyone know of a replacement needle or where to find one? Thanks Hollow Point PS: I originally thought (and still wonder) if the carb intake boot from the carb to the airbox is too restrictive? I seem to have eliminated that issue but I still wonder if this semi flattened tube is part of the problem?
  2. Just for your info I have the same problems with my 99 TTR-225. It starts like crap if it has sit for more than a few days. I know now to shoot some carb cleaner into the snorkel hole before I even try to start it. But if it's been run in the last few days it starts great. It's almost like all the fule is running out of the float bowl very slowly. I do plan to try the 42.5 pilot jet in place of the stock 40 to add some more fuel to the low speed circuit but right now I'm still fighting the high speed missing issue. So, I guess I have a poor starting issue as well as a top end problem. What's really weird is, I still like the bike even with it's problems (sounds like my 03 RX-1 mountain). Hollow Point
  3. TSK350, thanks for the information. 132.5 was the right size for the main in your case? Could it be that I'm too rich with a 135? I must say it sure doesn't sound rich to me but I'll try the 132.5 I have in the garage. When you guys say you opened up the airbox. How exactly did you do it? Did you retain the stock filer and metal screen? Have any of you used after market air filters with much luck? Thanks
  4. I thought I'd provide an update and ask a few more questions on this issue. I haven't been riding the TTR much these days. I have been out riding my BMW F-650 with the wonderful single cylinder 650 Rotax four valve motor but I did go for a short ride the other day. I don't think I'm hitting the rev limiter. Here's why. I was crusing down a gravel road and if I whack open the throttle and leave it there the missing just about makes the bike die. If I let off a bit (say 3/4 throttle) the bike continues to accelerate and gain RPM. I can go considerably faster with the throttle backed off. It's really a pain in the neck! So, I traded in my 42.5 bleed jet for a 42.5 pilot jet (not that it will help much on the top end). I keep thinking the problen has something to do with the nearly squished rubber intake tract coming from the airbox to the carb. I'd love to try just a K&N on the carb to see if it makes a difference. So, where do I go from here? I have a 135 main, the pilot will be a 42.5 shortly, the fule screw should be where with the 42.5 pilot? I have it it at about 1 1/2 turns out now with the 40 pilot and notice it still needed a shot of carb cleaner to start. I guess I need to hit the kill switch when it's happening an read the plug again? I bought the Big Gun exhaust because it was doing this with the stock pipe after I opened up the airbox. It seem that screen that slides in front of the airbox filters has a function because it seems to work a bit better with it installed. Enough yapping. H-E-L-P Hollow Point
  5. I swapped my pilot back to the 140 and my idle is wonderful again. Yes, the 142.5 pilot jet had little holes down the sides of it. Is this a bleed jet instead? If so, what differences does it cause? Maybe a REAL 142.5 pilot jet would work much better? I tried the bike first with the airbox cover on and the snorkle and the filter screen removed removed and the bike worked ok but still missed. Then I removed the airbox side cover and it seemed to work even better. I may cut out the side of the cover like someone on here did earlier. So now I have a 135 main, a 140 pilot, fuel screw at 1 1/2 turns and the bike seems to work better. It still misses a bit but if I treat the miss as a rev limiter and shift earlier it seems to pull hard and not miss. Thanks Hollow Point
  6. Maim, I guess we have more than one thing in common? It seems weird that leaning the jets down would work but at this point I'd try just about anything. Thanks Hollow Point/ Frosty/ Powder Blue/ etc.
  7. Today I made sure I had a 135 main jet on the bike. I also upped the pilot from the stock 140 to the recommended 142 and it barely idles it's too rich. I played with the fuel screw (once I drilled out the the brass plug) and it was at about 1/4 turn out from seated. I tried 1 1/2 first and it was horrible. I turned it to 1 turn out and it helped. I tried 1/2 turn and it was better and just cracked from seated (1/8 turn out) it's about the best it can be. I am at about 2,800 feet here at the house so maybe that has something to do with it. I think my stock 140 with the fuel screw turned out to 1 1/2 to 2 turns may work better for me. I pulled the needle to try to raise it a notch but it only has one notch so there was nothing to be gained there. I took it for a ride and at WOT (wide open throttle) it was missing like crazy again. Dang I had hoped I fixed it some how. Does anyone have any other ideas? Thanks
  8. Thanks Alyx, I do have a larger main jet installed. I haven't messed with the pilot jst yet but I will bump it up a size as you say. If I'm not mistaken the pilot jet size should have little if anyhting to do with my top end missing. I will bump it up anyway to improve the starting and decrease the warm up time. I am finding the motor pulls its hardest when it almost feels like I am lugging the motor slightly. I'm now shifting earlier than before and it seems to help by keeping me a way from the rev limiter (if that's what it is) that's causing the missing. Thanks for the info Hollow Point
  9. Thank you for the response. I suspected the rev limiter but I'm guessing I'm not close to 10,000 RPM when it's happening. This is a guess but I'm thinking it's in the 6 - 7,500 range (WAG) where it's happening. Are you sure the rev limiter kicks on at 10,000 RPM? Is there an after market rev limiter that SAFELY raises the RPMs the bike will pull? It sure doesn't sound like 10,000 RPM to me. I ride a Yamaha RX-1 Mountain snowmobile all winter with a R-1 4 cylinder 1000 four stroke motor turning 10,600 RPM and that's with four cylinders. I also have a BMW F-650 with a four valve Rotax single I ride and it turns no where near 10,000 RPM redline. The redline is 7,500 RPM. It sounds like I may have to rig up a remote tach. Thanks again Hollow Point
  10. Hello, I'm brand new to this forum and wondered if perhaps you guys might be able to help me out? I have a 1999 Yamaha TTR-225 I used for nothing serious for years, just some grouse hunting in the mountains in the fall and trail riding in the summer. I thought all was fine with the bike until a buddy invited me to go to a ORV park and climb some sand dune and steep trails with him. The bike was stock at the time. I noticed a couple years ago the bike didn't like the screen removed. So I had the snorkel on the airbox cut back to improve airflow. At the ORV park the bike would climb well initially by start missing horribly at WOT. I though huh, I have never pushed the bike this hard before maybe there's not enough air flow with the little stock pipe outlet because the plugs looked good. So I added a Big Gun pipe and it sounds really cool and the low to mid range is MUCH better but it's still bucking and farting at WOT. It's horrible! So, I thought maybe by adding the pipe I have thrown off the air balance between the intake and the exhaust? So I added a Thunder Products adjustable low boy sliding air filter on the side of the stock air box and tried it from all the way closed to all the way open and it still misses at WOT. So then I pulled the cover off the airbox and tried it to ensure I had enough airflow for the new high flow pipe. It still does it. Ok, now I'm getting pissed. Since it pulls well in the midrange I didn't mess with the needles but thought I'd try bumping up the mains a couple sizes to see if it helped. I went from 130 mains to 137.5 and it does the same thing. I then added a dial a jet to the system with the thought that it might fill in any lean spots in my carbeuration. Still does it. I pulled out the fuel petcock and checked the screens on the fuel intake and they were clean. I checked the ground on the coil for the spark plugs and all looked well. I broke them loose and retightened them. The plugs look good and I still have the problem, what now? I have cleaned the carb as well but not adjusted anything but changing the main jet. I have tried the bike with the snorkel removed and installed, a modified snorkel installed, airbox cover removed, dial a jet all the way from lean to rich, I changed plugs, plug caps, etc. I suspect I'm hitting the rev limiter but without a tachometer it's just a guess. I could put a remote tach on the bike but I have no idea what RPM the rev limiter is supposed to kick in. I know this bike was never intended to be a power house but not being able to open up the throttle really makes it tough to drive in certain situations. Any help you could offer would be appreciated. Thanks Hollow Point