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I ended up buying a motor last night for an AF conversion. it is a 98 and I pulled the head, and there is still fresh cross hatching and the piston looked pretty new. my only concern with the jug is that there is a hole drilled and tapped on the jug right by the "491cm3" where the reeds go. I figured that I could just cut some threads off of a bolt and install it flush on the inside unless someone can tell me what it was for. But I picked it up for $400 so if I have to replace the jug I dont really mind. other than that the engine seemed to be in really good condition.

Its most likely a hole that was created to run a fuel pump (probably about 5/16" in diameter, and accepts an 1/8" pipethread fitting). I've closed the same hole up with JB weld and sanded it smooth. It'll look alot cleaner than a bolt. Plus if you want you can hit it with a coat of paint and you'll never know it was there .

I thought about that but I wasn't sure if it would vibrate loose over time and fall in have the motor eat it. The reed cage should stop it but im just a lil nervous about it.

It should be fine. I've had a couple motors done that way. Just scuff the inside and outside of the reed box and the JB will bond to it. Plus if the hole is tapped the JB will fill the threads.

Might be a nitrous nozzle port?

thats a nitrous port homies

got a picture of exactly where the hole is ? im betting its vaccum for a pump.

Not too many motors out there WITHOUT nitrous that need a fuel pump...

Not too many motors out there WITHOUT nitrous that need a fuel pump...

X2
or it was used in a kart, which is just as bad

100hp honda wrote:got a picture of exactly where the hole is ? im betting its vaccum for a pump.

X491

i cant see someone spraying into the side of the reed block. need photo to see exactly where hole is though

there is a hole drilled and tapped on the jug right by the "491cm3" where the reeds go

thats pretty specific

2strokeforever wrote:

there is a hole drilled and tapped on the jug right by the "491cm3" where the reeds go

thats pretty specific

you could spray anywhere really because its going to end up on the top the piston sooner or later. logic doesnt say put it there though . brit or stouffers could probly better answer im sure

there was a sand or beach drag bike from australia pictured here or traces site not that long a go that had a spraybar for fuel above the reed in the closes to the bore marked area like that last picture.

A nitrous nozzle would hit the reed cage if screwed in right there. more then likely its for a vacuum pump for a kart or to run methanol.

Just get a 1/8NPT plug (if its 1/8) and plug it

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2strokeforever wrote:

Not too many motors out there WITHOUT nitrous that need a fuel pump...

X2
or it was used in a kart, which is just as bad

Whats wrong with having a 500 on a kart?

Whats wrong with having a 500 on a kart?

nothing, other than it prolly gets the piss reved out of it all the time... it still could be taken care of tho, but if it wasnt
kinda like buying a 125 that was only rode in the sand dunes

Just checking.

Both of mine spin 9,000+ constantly, and yes, they are very well cared for. Rings every 4-5 nights, pistons every 8-10 and a fresh bottom end every winter.

Both of mine spin 9,000+ constantly

how long till the piston cracks with those kind of revs??
or do weiscos crack at all??

2strokeforever wrote:do weiscos crack at all??

They do with nitrous.

Honestly, I've never cracked a piston in 5 years, even with .007 clearance. And I've ran one clear up to 17 nights, with 15 on a set of rings.

Of course, a 'night' is truly under 10 minutes of constant hammering.

I've really only used Wiseco. My spare motor, which I keep in the trailer piped, radiator plumbed and filled, ignition mounted and complete intake installed to allow for a change from blowup to fired in under 10 min, has a Vertex with 1 night on it.

so its more of a issue with high hours?

Yep. It's pretty much the same as a bike. Tme and wear create a loose clearance and piston cracking, generally. It's accelerated in my application due to the loose clearance and high RPM's. Do I need to change them that frequent? Probably not. But it's insurance against cracking and breaking.

I'm likely going to convert to Vertex because they're alot cheaper and my frequency of changing them out. That leaves me more money to spend on fun stuff to make it go faster

Thats definitely vacuum port as the reed block hasnt been drilled...