SCORPIO_2727

I aquired 2 K & B 65's off ebay. To bring these motors up to scratch, I ordered and received the necessary parts from K & B Manufacturing in the States. I now find I am one exhaust bolt short. Being manufactured in the U.S I was under the opinion the thread would be S.A.E. Wrong. They look and roughly measure as 3.5 mm metric, but still not correct. Further, an Imperial Allen key fits in the head perfectly!! Can someone enlighten me as to what thread K & B use? I want to try and find them locally here in Oz, rather than send to the States for a couple of small bolts. Thanks in anticipation. Glen

jetpack

My Feedback: (1)

3.5's are close to 5-40 standard. If you have a Cox .049 around, pull the prop screw and check. 5-40's are used in manufacture because it neatly fits a 1/8" drilled hole.

Sorry I dont own your KB. This is just a guess.

rcdude7

My Feedback: (264)

Glen, It is probably a 5-40 thread just like the K&B .61 muffler bolts. When I needed spares, I could not find locally, so I ordered them over the internet.

I don't know how common the imperial size hardware is in your area, it is here except for the 5-40 size, I'll never understand why K&B didn't just go with the very common 6-32 size thread.


Mike

SCORPIO_2727

Thanks jetpack and rcdude7 for your response. I was starting to wondering if some exotic thread pattern was used by K & B. I'll now dig out one of my Cox .049 and try the prop screw. 5-40. Thanks, now I know what to look and ask for. Being able to buy locally may indeed be a problem. If I have to buy from K & B in the States, I'm going to feel a bit of a twitt ordering 2 socket head cap screws, 2 and 1/2 inch long using my visacard. If I have to, so be it. Thanks Glen

jetpack

My Feedback: (1)

Hi Glen,

I just been through all this screw hunting myself for a couple engines, and went through all my screw suppliers but unfortunately everything in the 5-40 size stopped short at 2". I think K&B got you on this one.

Be sure to use star-type lock washers under the screw heads. Muffler bolts are notorious for loosening up. It is the expansion and contration of aluminum verses steel that does it. The star washers act like a short spring and keep things tight. Blue loctite can be used but that loosens up under heat but does slow down the chances of losing them. A standard split washer isn't too effective in this case. K&B might even supply them with the screws when you order. Webra utilizes these star types with their engines.

I would hate to see you go through the expense of buying and waiting for a couple of screws just to have them loosen up and get lost in the air.

I use a trick that dirt bikes have used for a long time, and thats installing a short stout compression spring under the bolt. The kind I've found are for RC Car clutch springs.

I don't care for star washers myself, because they tend to dig the aluminum each time you remove them and pretty soon the screw seat is tore up adding to the problem. I run marine motors, so the header usually gets taken off after the day is done to properly flush and store the motor.

You could also go with drilling small safety wire holes through the heads of the screws. Its a pain to do though, small drill is necessary and using wire isnt fun or neat looking to hold them.

AMB

The shipping cost will more than the screws i would get 2 or 3 sets martin

SCORPIO_2727

Thanks for the input everyone. Local efforts, state and interstate efforts here in OZ met with a resounding no, we don't have it, we can't get them, but we can have them made. Gees. Like trying to find hen's teeth. So looks like I'll be using the old plastic card trick to buy from K & B themselves. And yes, as AMB suggested, I'll buy a few sets while I'm at it. Glen

Hobbsy

My Feedback: (102)

Scorp, I have an old K&B .65, I know that the muffler from my .61 Twist fits on it perfectly. I think the bolts are 6x32s, I'll check tomorrow with a ScrewChek'r. Don't laugh, that's a real brand name.

SCORPIO_2727

Thanks Hobbsy. Would you be Hobbsy from the diesel forum? If so, I too am a model diesel fanatic. Also another motorcycle enthusiast. Until 3 months ago, I had a collection of 40 of the old Suzuki two strokes. But unfortuniately, none of the my many heaps of spare parts fit the K & B's. Sorry, I did laugh at the mention of ScrewChek'r, most appropriate when I'm being screwed around trying to obtain screws. I'll wait till I see your reply before I flash the card. Glen

Hobbsy

My Feedback: (102)

I am the same, interestingly my son in Providence, Utah own 120 UJMs of various makes and models, knows the weaknesses of each and every one. He bones out the worst ones and makes good ones out of the parts. All are fourstrokes. My friend Francis is another Oily Rag Brigade dude and tried to run a K&B .65 but had no luck. I am trading my .65 in at Fox for a Fox .74, I love those big Fox'.

Hobbsy

My Feedback: (102)

These are 6/32x1.5"

SCORPIO_2727

Thanks everyone. I've bitten the bullet and ordered 3 sets from K & B. (I'm only short of one lousy screw). The postage for 8 oz air to Oz is the same price as the 3 sets. At least my problem's solved. I"ll probably forget where I stashed the 2 spare sets if and when I need them in the future getting old and senile. (Where did I safely hide them?) Thanks again for all the input. Glen

jetpack

My Feedback: (1)

One day you'll get tired of putting them here and there, forget what they are for and toss them in the trash to finally get them out of the way, and then needing them the next week.