(Yamaha 650 cases with different intake ports welded on)

[ryno_281]

Need some help here. Rebuilding kind of a weird old school specimen right now. 6m6 cases, 61x cylinder, dual intake ports welded on and a custom made intake manifold with dual 42mm sudco cdkII’s. Oh and a genesis head and protec pipe. Weird setup but it rips in my fx-1. Anyways, I need to know what reeds these are or what the bolt pattern looks like it’s off of in order to get new reeds and gaskets. I heard some of these setups ran kawi 750 intakes but this doesn’t. Any help appreciated

 

[Quinc]

@TheBuzzard is the all knowing historian that can tell you exactly what it is and provide you any parts you may need.

 

[ryno_281]

Dang! You left out the photo of the modified 6M6 Crankcases! lol

I’m gonna add one to this thread, forgot to snag a pic before I left my shop last night!

 

[Andrew1289]

I’ve got a set of these. Been on the parts shelf for years. I think it’s 750 reed cages

 

[Andrew1289]

Photos of mine

 

[ryno_281]

Here are some more pictures of the engine

 

[yamanube]

@Andrew1289 has a 750 intake but @ryno_281 has something completely different. Doesn't look like any watercraft setup from that era.

 

[ryno_281]

@Andrew1289 has a 750 intake but @ryno_281 has something completely different. Doesn't look like any watercraft setup from that era.

I didn’t think so either, doesn’t look like any of the motorcycle stuff I looked up either

 

[Storbeck]

This is a pretty long shot but I have a vague recollection that my yz250 Reed has a bolt pattern similar to that. They were the same from something like 1999-current model

 

[ryno_281]

This is the ski that I bought with this engine in it, the gal I got it from told me who originally built it but I can’t remember his name. Pretty sure he was based out of central California. I don’t think it was the ski clinic but I could be wrong

 

[Storbeck]

https://www.ebay.com/itm/99-YAMAHA-...:YZ250&hash=item48e1ee6191:g:wpsAAOSw44pebPV7

 

[SUPERJET-113]

Thats what they did before 62T cases.. 6M6/61X cases with kaw 750 intakes welded on, like Andrew1289 above, but yours only have 1 bolt hole on the bottom of the intake and also the side hole is down low instead of being in the middle. Its not Yam or Kaw, or anything that Ive seen before in 30 years of messing with these things. Weird...

@Storbeck is onto something with the bolt pattern, but to small cages/ports.

@TheBuzzard lol

 

[ryno_281]

Here is a yz250 cage next to the John Doe cage, pattern is the same but the dimensions are definitely smaller on the yz cage. Good on you @Storbeck we’re close!

 

[mikidymac]

TDR can make you a new set of reeds if you send them an old one but not sure on the gaskets.

 

[ryno_281]

@mikidymac I can make a new set of gaskets if I have to, that shouldn’t be too hard. The reeds definitely need to be replaced though. I’ll see if I can get ahold of tdr about it

 

[Storbeck]

Maybe an old KTM?



https://www.ebay.com/i/252335007600...1C9WXA3QDZmeffYO0DQ6ymGMp8WRYiZhoC_tsQAvD_BwE

 

[TheBuzzard]

yea, I got 2 sets of those floating around here someplace. 61x cases with the kawi 750 intake track welded on. pre 62t mod. I cant remember who did this but I know i'm losing my mind. I was just pulling my hair out wondering why this blaster wouldn't pull fuel. I had the lines hooked up backwards. yea that aint the kawi 750 setup like below. maybe polaris. funky bolt pattern for sure. probably works good. looks like keihin carb or i series mikuni if i see the angled carb footprint correctly

 

[Pro-pulsion]

The closest I could find for you is that it appears to be 2 flipped upside down 1986 Suzuki RM250 intake tracts. The 5 bolt pattern, the 4 finger cages, it looks right.

 

[john zigler]

This was a popular mod back in the day, like stated before 62t cases. RIVA did these, but used Kaw 750 reeds, intake, etc. Looks like this may be a home done one, obviously the reeds are now Kaw 750. At 1st I also thought it is some kind of Polaris, as the reed cage has a rubber gasket built in like Polaris does, but it Looks like Pro-Pulsion is onto something with the Suzuki Reeds.....

 

[MTRHEAD]

These were eventually outlawed by the ijsba after one cracked/failed during race. There were 2-3 shops offering this service. Trickest ones angled the reeds up more than the 62t design so then side drafts were used (on couches)