Hardcore

Well it only hit the low 40s today and I took my KDX 200 out from storage to see how it looked on the plugs. In the summer/fall it's tuned perfect- chocolate brown all over. After warming things up and going through the gears using the full throttle range, the plug showed grey on the porcelain just as the Blasters do. I feel confident now that the quads are where they need to be for three season riding. The plugs are reading lean simply due to the fact it's damn cold out. I have been tuning them in a semi-warm garage and expect them to react the same with a cold ambient temp and wind chill once outside. Not gonna happen. All I need is a warm day to be sure this is whats happening. Just thought I'd share that even though no one wants to input on this. Hardcore.

I just spent several days cleaning and rebuilding two '96 Blasters. One is bone stock and needed no adjustments - engine operates flawlessly, starts well cold/warm and throttle is clean through the rpm ranges. The other I had to bore over to 0.5mm over stock. After the bore and top end rebuild I found that this bike wanted one pilot size smaller than stock. OK. Everything was responding well on both again so after a complete break in on the one, a friend and I went out for a rip with the kids. After I put them away for the day I figured I'd check the plugs to see what they were saying. The stock Blaster was grey to dark brown ( a little lean I'd say), and the one with the over bore was grey. "Oh!" I said. It was a lot colder outside than I thought it would be (32degrees F) and hope that this was the reason behind the plug colouration, because there were no indications that they were set up lean - float level is perfect, air screws out 1.5 turns out, needles in mid clip and one above mid for the over bore, and the mains are 240 and 250(stock is 230). I don't want to set these up by going on the plug colour alone. What should my next step be here? Tomorrow is supposed to be in the 50s. so I'll try them in that temp and see how they are. Thoughts?

Well I fixed it. The piston measured out to be 0.007" smaller than the cylinder bore - way too big. The new piston calls for 0.0015" to 0.00175" clearance but I asked to bor it to 0.0025", the other just seems too tight for an air cooled 2-stroker. The rod bearing play is normal as per the Yamaha dealer, a race engine builder and a machinist. I thought it might be but these guys have all the experience and wanted to make sure. Just thought I'd share this all with yas. And when I say rod play, straight up and down there is just a minor amount that you can barely feel. Cheers folks.

Thanks to all the replies so far. I checked things out for external rattles but came up short. While I had it running I did the old screwdriver to the ear trick and poked around the top end and noticed the noise loudest right at the top of the cylinder and head area. Sooooooooooo. I ripped the top end apart to check it out. There is no play in the top bearing but there is just a little, tiny bit of play in the bottom bearing when I pull derectly up and down. Just enough that it can barely be felt. I'd guess a one to two thousandths of an inch. I know the side to side and rocking back and forth play is normal but straight up and down? Can there be any play there at all? Is this normal? I ask because there is a hell of a lot of play between the piston and the cylinder wall. I know there is supposed to be some for the rings to soak up but I think there is too much and this is my problem. I plan to order the next bore size piston, rings, etc and get it bored over to match the piston and reassemble. Any thoughts here? Do I need a bottom rod bearing relaced or just the top-end as I suspect? Please help. Hardcore.

You guys have helped me out with my 87 banshee, now how about help with a friends' Blaster? It's a 1996 blaster. Single cylinder. I just started it up after a minor tune up and the thing has a major rattle in the top end. My buddy has another blaster I tuned up yesturday and it sounds normal. What could this noise be? (the bikes were given to me to clean up for the coming riding season - I have never heard them run before so I assume this has been rattling for a while). The compression checks out at 140psi and everything else is normal. This noise is real loud at idle and seems to smooth out when I rev it up. Top end bearing, cracked piston skirt,bottom end stuff?????? Any input would be great. Thanks,

Amen. That's what's going on here. I've been chatting with another dude on the subject and he's been trying to explain the choke circuit to me. My bike's carb bowls are reversed. The way it sits, there isn't any way the fuel can come up from the bowl. I see now. I know I'm new here but, if someone with a digital camera could post pics of their carb bowls and the under side of each carb to show the differences and why, this would be a great help I'm sure. A drawn schematic of the choke circuit would be good too and would compliment the pics. Just my two cents. Thanks for the advice. Now just need to rebuild. Hardcore.

Thanks gents. I speced out the cylinders and they're in great shape so I'm gonna try a new top end at this bore size for now. I have been running natural oil at a 24:1 ratio. I'm gonna switch to synthetic like run in my KDX. So you say 40:1 will be OK? I may start with 30:1 and see how she likes it. And before someone bursts in here, yes I'll break it in with real oil then switch to the synthetic. Thanks again guys. Hardcore.

Aaaaaaahhhh. I finally got onto the site. Here's what's goin' on. 1987 banshee. RX350 topend with the power valves rigged in the full open position (all the time). This bike was bought originally from a flat tracker. The bike runs well. Starts and run well in the summer but in the winter it will not start. The only way to get it started is to pour fuel in from a cup! And, once it fires, it runs great. What is the problem here? What to check? What to change? I canged out the reeds, they were bad. Boyseen went in, cleaned the carbs and checked the jets - 290 mains and 27.5 pilots, mid clip. Air filter changed out for a new one too. After all this is runs crisper but didn't change the cold starting problem. The static compression is 105 on each side. This seems low right? I now have the jugs off and the bike has 1.00 over stock Wisco pistons in it. Also I noticed that there are 3/8th inch reed spacers between the cyloinders and the reed cages. What will these spacers do? SO. With better compression, reed spacers out, will this fix my cold starting problem? Will the power valves in the fully open position hamper my cold starting? If so, why doesn't it happen in the warmer weather? Side questions: The book says to run 24:1 oil mixture. What oil ratio do you folks recommended here? What brands? What is the normal static compression of an '87 banshee? 150psi? !!!!!!Which carb should have the the pick up tube in the bowl? Pick up tube on the Right carb(passenger side)? !!!!!right? fuel comes over from the right carb and feeds the left who has the actual choke knob. thanks for any/all your help. Sorry for the long post but I've been racking my brain on this one for a while. Well, a week anyway. Hardcore.