Roketa MC-62-250 By damin69 (Read 5,821 times)

[paulpaul]

I was just looking at his plug. Why does the carbon go so far up the treads on the plug. That would mean the plug treads are going past the treads in the heads . Is he running to lone of a reach plug in that motor? Thanks Paul

[JR]

No that's the right plug, but it does make me wonder if he's got a head with loose threads and is loosing compression at the spark plug?

JR

[paulpaul]

OK got the bike back together enough to crank it. It ran OK till choke went off . Then i had to set the idle and it seem to be idling a little rough. I thought it might have a vacuum leak so i sprayed ever thing with water. No change. When i revved the motor up it didn't want to go up to rpm. It would stumble at about 45 hundred rpm. I had changed antifreeze and i noticed the gauge was running to hot. revved motor it went up to 6000 fast. I cut it off and let it cool. Checked coolant level and add some. I cranked it up ran like a dream all of a sudden after i revved it to 6000 it would not idle again had to move idle screw for a smooth 1500 idle. Cut it off let it set ,cranked ran perfect. Still to hot. How do you know when you have all the air out of the cooling system? And what is the best way to get the air out. Also i noticed that when i revved the motor up the temperature gauge would fall and when let off the gas go back up. Any ideas? At least it will go up to rpm up some times!! Thanks in advance Paul

[JR]

thescooterprofessor.proboards.com/index.cgi?board=cool&action=display&thread=24

Paul it can take several times to get it all out and if there is any air in the syatem not only will it run hot but most of the time the cooling fan will not cycle on and off, won't even come on most of the time.

The above mentioned burp has always worked for me and I've even told some to take the scooter for a ride around the block and let it get bone cold before doing it again.

JR

[paulpaul]

Thanks JR!! I thank you for your time and trouble. Paul

[speedracer]

I am not one to brag at all but after Todd posted his spark plug picture I made the comment that his plug has oil on the treads. The only reason I mentioned it is because I've pulled my plug many times to see if it was running rich or lean. Only a few threads on the plug had carbon on them.

[damin69]

Sept 3, 2011 5:40:03 GMT -6 JR said:

No that's the right plug, but it does make me wonder if he's got a head with loose threads and is loosing compression at the spark plug?

JR

Ok this sounds feasible. It has not been loose taking out but for testing sake what do I do to seal the thread up? Some Plug antiseese I will go get a new Plug also. cheap enough to just try it.

[saved2share]

Sound like you have a small air leak...maybe a hairline crack in the "L" shaped carb intake snout. That was what was wrong with my 260cc.

[paulpaul]

My 250 is running better. I can get the rpm now. The vacuum hose that comes from the vacuum canister to the air box had cracks in it . I cleaned the breather filter and put filter oil back one it. Also the large pipe that hooks to the carb and is molded to air box and is sealed had cracks in it .I sealed with Yamabond grey. I believe i have mine repaired. I will have it back to gather this week some time and we will see for sure .Thanks everyone .Paul

[JR]

Welcome to the forum saved2share and that is a very good suggestion on the intake manifold and just food for thought on that idea, I read about a guy who was having this trouble but only after it warmed up, when cold it would run like a scalded ape.

What he finally figured out was this tiny crack when cold would seal off well and when warm it would open just enough to cause this trouble. aAuminum can do this sometimes when other metals will close up a crack when warm.

The intakes are aluminum with a rubber outside mold around them and are notorious for cracks and bad seals.

At this ppint with all that Todd has tried from the common sense stand point and from proven how to repairs we've all got to think outside the box to find this gremlin and when we do then we can all have the knowledge if this ever happens to anyone else.

Also great to see you up and running well Paul and keep us posted and for sure those cracks in housings and hoses can cause a lot of grief.

Hang in there Todd we're all thinking on it and just added a new member who is jumping right in and making good suggestions.

JR

[paulpaul]

If you find a crack on the intake manifold instead of replacing it go to the nearest place like ( Yamaha dealer) and buy grey yamabond gasket maker . Put that on it it will set up like rubber and last a life time. It is one of the best gasket makers out their. Someone may know another name for the same thing.

Now to my trouble on no power. I was checking all plug and tightening them. Noticed that the 3 yellow wires coming out of my rectifier were really hot. I checked for loose connections at the plug. These 3 wires go to the same plug. They leave there and go to the stater. All three wires a hot. Is this normal. I thought i might have a rectifier going bad. I did a meter check at the battery a little over 13volt dc I revved up raised to 14volt dc. I have had rectifiers start to go bad an still read right on dc scale but when you switch your meter to ac the rectifier is starting to go bad an has ac voltage going out to your system. At first you want know it with out checking . The you will start having things happen. It will ruin your battery and almost any dc unit on the scooter. You should not have over .002 ac volts when you read ac on the dc system. Your stater is putting ac volts out, the rectifier converts that to dc volts . I hope this helps anyone having electrical problems that are weird. By the way mine was OK. But the three yellow wires are to hot. Thanks for any help Paul

[paulpaul]

HI! Damin 69 !! Just for a chance check the plug that the three yellow wires coming Of the rectifier and see if after the motor has run for about 5mins if the yellow wires are hot. I had the same problem you do and i am wondering if you wires are hot like mine . I notice my scooter idles up and runs perfect when i unplug the plug with 3 yellow wires. I must have a short where those 3 wires go. I'm going to eliminate them i at a time. The 3 yellow wires go to the front of bike.One is the charging wire. They are coming from rectifier to the front. I', m going to look for a diagram and see where each wire goes. Thanks Paul

[paulpaul]

I did what i was told. I changed the connector on the 3 yellow wires from the rectifier. It's fixed. I guess it was robbing power from the system and not getting a good spark and weaken the power. She will go to 7000 rpm now. Thanks Paul

[damin69]

Thanks guys. I will take a look at all of the suggestions when I get some time to get in the Garage. I have already looked at the Intake manifold looking for Air leaks.

I had not really looked at electrical. hmm. Since I am not the first owner and the Previous owner did a PISS POOR PDI as far as I can tell it would not hurt for me to check out all the electrical connections at all.

Thanks.
Todd

[damin69]

.roketa.com/product/parts_detail.jsp?partId=42061&partName=F9.AIR%20CLEANER%28%E7%A9%BA%E6%BB%A4%E5%99%A8%29" rel="nofollow" target="_blank">.roketa.com/product/parts_detail.jsp?partId=42061&partName=F9.AIR%20CLEANER%28%E7%A9%BA%E6%BB%A4%E5%99%A8%29

Ok after reading the other thread of no power hill climbing it got me to thinking about this air box. THE previous owner did a crap job on this scooter which got me to thinking that maybe the Air box might have been modified. It looked like someone might have cut a piece of plastic out which would allow more air in than what would normally be allowed in.

Does any one have pictures of the stock air box shown in the link above? I would like picks of all the ports on the bottom.

Thanks a million in advance.