1995 Blaster piston slap? or somthing else

[paulrizik04]

1995 yamaha blaster

the problem: the engine makes a clear metal gringing sound when tring to turn it over. i thought it may be the piston but it looks ok to me(novice) when i pulled the jug both rings where in properly. i didnt see one out of its groove and ring gap was at the pin on the piston. on the jug i noticed a very small scratch but cant feel it to the touch. the scratch is on the carb side when engine is assembled. i checked the piston and rings where the contact point would be and cant see or feel any abrasions. i rebuilt topend 3 seasons ago. but about a month in rideing running good the rear bearings went so the bike sat for a few years. i fixed bearings and then tried to start it and suprisingly it started after just a few kicks. good gas and all before starting for first time. ohh i did mix my gas differernt this time. i ushally mix 32:1 but i mixed at 36:1 this time. slightly less oil. it was running rich before lots of smoke and seemed to hesitate a little. it seemed to start alot easier and i think it was because of the different mixture. so after starting so well i left the bike running for about 10 minutes. it idled very smooth and nice. before id have to rev it a bit to keep it idleing. then i got on and did a few circles in the lawn and it seemed to run well. lots of power compared to before if you gave it alot of throttle at once. so the next day i figured id take it somewhere to ride/work on it. got there and started it up on second kick. and let it idle for about 20 minutes. Again never ran this well and i think the new mixture is the difference. the idle did seem to hang so i started adjusting the air/fuel screw. out is more air in is less air. stock is 1 and 1/2 turns out from lightly seated. from stock setting i slowly started turning it out but only got worse so i turned it back to stock then started turning it in. i got it close to where i thought it should be. idle seemed to be jsut a little better. so i got on and rode it down the field and then i could tell it was starting to lose power and run different. i could hear a sound from the motor that sound like piston or rings was sticking or something. so i let it idle back most of the way back. but it was getting worse so i shut off the bike. it was a long push back. i got on it and with no intention to start it slowly pushed the kickstarter through it motion and can feel and hear so clear metal contact. so i read about all the things it could be but figured i wont know anything until i rip it apart. the only problem i see is the tiny scratch on the carb side of the jug. i know the scratch shouldnt be there but i dont see what caused it and what is creating the sound im hearing. today i took it all apart hoping to find out what the problem could be but the piston and rings look good and the clylinder looks good other then the tiny scratch. the rings gap isnt close enough to create the scratch. i was thinking maybe the rings came out somehow and created the scratch and the noise but they where in the gooves on the piston and appeared to be in the right spot with the pins on the piston when i pulled it. im putting the cylinder back on with the rings in correctly again to see if it makes the sound still. if i reseat the rings properly and put the jug back on i should be able to recreate the issue. if not then i think it could hve been the rings somehow. i have a few pics but cant upload them. i will try and post pics somewhere then upload them from there to here. i know i need to check the clearence between the piston and the cylinder wall and i know it should be less then 1mm. i dont have the tools to measure it.

 

[paulrizik04]

yo anybody out there? i know someone has to have an idea about something. any help is welcomed. im stumped. im thinking of taking the jug to a shop and having them look at it. should i go ahead and remove the piston? i need to make sure the clearance is within tolarance anyway. i dont know why pics didnt work. it shows them uploaded but shows red X over the pic. is pic to large?

 

[blasterdemon7]

Sounds like it was running lean and starting to over heat. It's hard to say what the sound could be without being there. You may have to keep check things out to find what it is. I would check the piston skirt to make sure no part broke off.

 

[Larry's Shee]

10 minutes is almost to long to warm up unless it's below freezing, and 20 minutes of idleing may have damaged it.
Hopefuly you have new gaskets for assembly.

 

[jus_me]

Hanging idle says air leak. Have you leak tested? . Could your noise be from clutch? Hard to tell without hearing it. Any way to post a video with sound?

 

[paulrizik04]

blasterdemon7

the piston skirt is on piston with no visable marks or dings dents by feel. this is what i figured i was hearing before i riped it apart. i didnt notice it any hotter then normal but after idleing so long i can see how that could have created the heat. i took some pics and a video with sound but cant seem to upload them. i think they are to large. not sure how to resize pics and video. might post elsewhere and make links if i can. could the different oil/fuel mixture have caused this? i ushally used 32:1 but seemed kinda sluggish and smoked some. i mixed at 36:1 and didnt figure it would make that much of a difference.

larry's shee

yes i agree with you i was jsut so shocked as to how well it was running. it never idled before always had to feather it a little but runs well. once i get the pics and video up i will make links. the only gasket i have to replace is the one the jug sits on. i left the head on the jug and didnt remove the reeds or rubber manifold. could the different oil/fuel mixture have caused this? i ushally used 32:1 but seemed kinda sluggish and smoked some. i mixed at 36:1 and didnt figure it would make that much of a difference.

jus_me

air leak? this is my weak spot. i havnt done a leakdown test after i rebuilt it. i was worried this might come back and haunt me. when i took it out and rode it/fix on it i let it idle for a while and noticed that after idleing for a while if i reved it up some the idle would hang a bit. so i started adjsuting the pilot air screw. first adjsuted out and nothing better nothing worse. so i readjsuted to stock (1 1/2 turns out) then turned it in a bit. and even with it within a half turn in seated nothing seemed much better. the idle would hang some. before if i adjsuted this i could see a difference in the running of the bike. so is it pulling air? the oild injection is removed. but the nipple on the carb isnt plugged. and never has been. my cousin owned the bike for 5 years sold it to my aunt she had it 5 years and i rode it alot and i never recall it pluged. but i still plan to plug it cause water or mud could get in there. could this unplugged nipple be the air leak? something else i noticed is that when idleing with this new mix or possibly something else it would rev real high real easy. i never heard this bikes rpms go this high. sounds more like a race bike with tons of mods or something. this bike is all stock. other then bore. i got a video and a few pics but havnt got them up yet. it didnt sound like the clutch to me. when the bike is in nutrual and i kickstart the bike i can hear the sound and feel it. i noticied that the two ports closest to the tiny scratch marks where not champhered much and thought maybe the rings where getting stick on it. i dont think the clutch is involved.

thanks guys i have to build my leakdown tester and find that leak!

 

[Blaaster]

Changing from 32:1 to 36:1 would have changed the oil content but would have also made the AFR richer by about half a jet size.

This change could be masking a small air leak.

Then if all is well set your float level and your idle.

Float level should 20 to 21.5mm on a stock carby.

you want to turn the carb and hold it on a slight angle to measure the float height, like shown here......

it should just barely be touching the inner needle, not depressing it,

It is possible to check the fuel level by attaching a length of clear plastic tubing to the drain nipple , lifting it up the side of the carby, and cracking the drain screw.

The fuel should show in the pipe to the level of the carb body above the float bowl gasket.

Idle adjusting.

Start with air screw 1.5 turns out.

Set idle screw so that it has some sort of idle. With TORS it is the big screw under seat on top of unit. With no TORS is is the brass screw midway down carb body.

Warm up motor and then set idle screw for a faster idle, 2000rpm+

Adjust air screw either way to get the fastest idle.

Adjust air screw a little at a time leaving 10 secs or until the motor to responds.

Re adjust idle screw for desired idle .

 

[j mcq37]

The carb nipple not capped is a clear air leak. Any idea what main jet you are running? Leak down test would be a good next step too.

 

[paulrizik04]

blaaster

you said", This change could be masking a small air leak." could you please elaborate. im a noob in many respects. new to this forum,2strokes, and atvs all together. im using what little i know from working on cars to bridge the gap. i will make a leakdown tester and find the leak asap!

j mcq37

the uncapped nipple has been that way for years now. never had a problem before. i will make sure its capped before i move on to rule it out regardless. main jet is stock 230 i believe. i will have to confirm that is the size in the bike tho. im sure it is but will make sure.

thanks for your help. keep it coming. ^^^^^^^AFEW PICS ABOVE^^^^^^

 

[Blaaster]

If I understand your explanation correctly, you mentioned that it ran better when you richened up the AFR by putting less oil in the pre mix.

With the combination of the uncapped nipple, a small air leak and a #230 main jet, the 36:1 fuel mixture would make it run better.

The extra fuel in the mix would help mask the problem of a too lean mix.

 

[paulrizik04]

ohh ok i understand now. the bike rode for years without the nipple plugged with no issues. so im not sure what is different now but will make sure to cap it regardless. i need to make the air leak tester asap to find the leak after plugging/capping nipple. thanks again blaaster for detailed reply. so do you think i need to mix at 32:1 or is 36:1 ok. i didnt think it would be too lean.

 

[Blaaster]

ohh ok i understand now. the bike rode for years without the nipple plugged with no issues. so im not sure what is different now but will make sure to cap it regardless. i need to make the air leak tester asap to find the leak after plugging/capping nipple. thanks again blaaster for detailed reply. so do you think i need to mix at 32:1 or is 36:1 ok. i didnt think it would be too lean.

32:1 is the minimum that you should be mixing for a motor under 200ccs.

I mix Castor oil at 25:1, for maximum protection, power and peace of mind.

Changing from 32:1 to 25:1 requires a jet change to one size larger.

 

[paulrizik04]

ok guys i understand i might have an air leak but not sure about this metal scraping sound. i can feel (what seems like the piston and/or rings sticking) i can hear the sound and can feel resistance through the kickstarter. so after i find/fix the air leak/leaks? will i have to replace the piston and rings? i cant tell exactly what and where the sound and resistance is. i understand i may be jumping ahead and need to fix one thing at a time, if so tell me. does this sound like a possible bad bearing? or bent piston arm? im worried it could be a bottom end job but have no idea or expirence that gives me any guidance as to what is making the scratching sound.

much thanks everyone. working on getting a vidoe up. can anyone give feedback on pics posted above. do i need more pics do these pics show any clues?

 

[Blaaster]

Question:

What was the reason for the rebuild 3 seasons ago, please elaborate?

By chance did you revolve the motor when you had the jug off?

 

[paulrizik04]

blaaster

when i rebuilt topend it 3 seasons ago it was because i thought it needed rebuilt. what actually happened was the flywheel woodruff key actually sheared off and wouldnt spin the flywheel. when i kicked the kickstarter i felt very little resistance so i automaticly thought no compression. so i got it bored at a shop and then ordered piston. then i knew the tolarance was supposed to be small. less then 1mm. i think .8 was the goal. i never measured it. the shop did all the work. so i reassembled with all new gaskets. and still nothing. then figured out it was the woodruff key. fixed the key and fired right up. i did the break in with about a tank and a half of gas. start and did heat cycles at least 5 times. then putted around after completely cool with no throttle afew times. then got up to about half throttle heat runs afew times. took about a week to do the whole break in. i will check the size of the piston and report back. i need to buy a micrometer to find the clearance between the piston and cylinder walls. or is it piston ring to cylinder walls? i did rotate the motor witht eh jug off. it is very smooth and i didnt see anything down in there. i can move the piston arm very little at the top from side to side but have no up and down movement so that tells me the main bearing is ok right?

 

[paulrizik04]

for some reason i cant upload them here but got them on photobucket.

copy link and paste into address bar to view videos

video 1 - dont mind the ting spound. thats the kickstarter hitting the foot pegs. it was hard to hear it. but you can see almost every kick got hung up.

vvvvv****LINK****vvvvv

Dont Mind The Ting Spound. Thats The Kickstarter Hitting The Foot Pegs. It Was Hard To Hear It. But You Can See Almost Every Kick Got Hung Up. Video by paulrizik86 | Photobucket

video 2 - showing scratch but cant see it well kinda blurry. and showing the main bearing test side to side and up and down. i didnt show it but engine revolves completely with no opstruction very smooth

vvvvv****LINK****vvvvv

Showing Scratch But Cant See It Well Kinda Blurry. And Showing The Main Bearing Test Side To Side And Up And Down. I Didnt Show It But Engine Revolves Completely With No Opstruction Very Smooth Video by paulrizik86 | Photobucket

after viewing please let me know your opinion. im thinking my piston rings are hitting ports that werent champhered properly but no marks on the rings and none on the unchamphered spots but small visual scratches right between the only two ports with unchamphered ports. machine shop did a poor job. hey everyone is doing a great job helping me out here. im glad this forum exists. i love my blaster!

 

[paulrizik04]

32:1 always worked well before. i should have stuck with it.

 

[gizzy2014]

you better get in there and chamfer those ports before u catch a ring and really make a mess of your motor.

 

[paulrizik04]

gizzy2014

ya i was thinkin the same thing but cant find any marks on the piston and rings. the scratches are right between the only 2 ports that wernt fully champhered. please look at pics and watch video an let me know what you think. when i try and kickstart it i can feel the metal contact and it sometimes gets hung up and sometimes it make a distinct metal scratching sound. if i champher the ports do you think id be ok or will i have to get the cylinder bored? let me know later man. And thanks alot too.

 

[gizzy2014]

gizzy2014

ya i was thinkin the same thing but cant find any marks on the piston and rings. the scratches are right between the only 2 ports that wernt fully champhered. please look at pics and watch video an let me know what you think. when i try and kickstart it i can feel the metal contact and it sometimes gets hung up and sometimes it make a distinct metal scratching sound. if i champher the ports do you think id be ok or will i have to get the cylinder bored? let me know later man. And thanks alot too.

if u just had it bored out... and never really used it...... u should be fine with just chamfering the ports, and if they are not chamfered like u say then they need to