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Thread: ISO Dirt Wheels article for Ascott 500 Head Install

  1. #16
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    Quote Originally Posted by RapidRick View Post
    Because the exhaust is under more pressure and therefore the exhaust gas velocity is greatly increased thus evacuating the chamber more rapidly?
    Yes that and we are not needing as much time so we don't run as long of duration on the ex. lobe anymore either.

  2. #17
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    Quote Originally Posted by big specht View Post
    ? I have a xr500 and ascot and stock 350 head if you want to some flow numbers? I would like to see the difference cause like Billy said it's one of those " one of these days projects" that I have laying around. But if it's not going to be worth the time ?and Mickey you are not all that far from me ?
    That would be fun, but not before Trike Fest I'm under too much pressure now to get things done.

  3. #18
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    I'm in no hurry I've only had most of these parts for 9 or 10 years or more so I suppose I can wait lol
    If its on the internet its got to be true they can't put any lie's on the internet

  4. #19
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    Dec 2002
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    172
    I came across a 350x with 500 head on ebay last year. It had the 500 head and rocker cover. For the oiling, there was a 90 degree pipe fitting on top of the head to oil the cam. The guy had taken a couple pics of the rocker cover and head when he had it apart and you could see they drilled into the right cam journal and milled a slot. For the head fasteners to the 350x cylinder problem, it looked like they just removed the two studs that don't quite line up in the cylinder and just ran with the 4 main studs. If you want to run all six, then you have to plug the cylinder or head for the one that doesn't line up, move the location, then mill the cylinder for the nuts to fit like Swigin did.

  5. #20
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    Quote Originally Posted by Tecate performance View Post
    I came across a 350x with 500 head on ebay last year. It had the 500 head and rocker cover. For the oiling, there was a 90 degree pipe fitting on top of the head to oil the cam. The guy had taken a couple pics of the rocker cover and head when he had it apart and you could see they drilled into the right cam journal and milled a slot. For the head fasteners to the 350x cylinder problem, it looked like they just removed the two studs that don't quite line up in the cylinder and just ran with the 4 main studs. If you want to run all six, then you have to plug the cylinder or head for the one that doesn't line up, move the location, then mill the cylinder for the nuts to fit like Swigin did.

    Yes you have to put a fitting in to get oil to the cam and rockers and you just run the 4 studs with no problems.

    But IMO it's not the best way to go, all of the valves pistons ect. are old big heavy stuff. My new 350x head uses 5mm valve stems VS the 500 using I believe they were 7 mm. Plus they are so much lighter and flow better then any head I have built for these, it's a no brainer to go light with everything.

  6. #21
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    Dec 2002
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    Yes, I have run your 92mm bore kit and megacycle 144-25 cam with a 41 fcr and 350x head and it's a strong reliable combo. I've since added a powroll 6mm stroker, and while the power increase was nice, it makes quite a bit of mechanical noise in what sounds like piston slap. When you used to stroke them did you offset the wrist pin or anything like that, or is that just a characteristic with them? I've run the 6mm stroke with the 92mm JE and a 94mm modified 450r piston, and it sounds the same. Also, do you have those green clutch springs back in stock for these? They are the best springs I've ever found, as they don't slip and have an easy pull and great feel.

  7. #22
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    Quote Originally Posted by Tecate performance View Post
    Yes, I have run your 92mm bore kit and megacycle 144-25 cam with a 41 fcr and 350x head and it's a strong reliable combo. I've since added a powroll 6mm stroker, and while the power increase was nice, it makes quite a bit of mechanical noise in what sounds like piston slap. When you used to stroke them did you offset the wrist pin or anything like that, or is that just a characteristic with them? I've run the 6mm stroke with the 92mm JE and a 94mm modified 450r piston, and it sounds the same. Also, do you have those green clutch springs back in stock for these? They are the best springs I've ever found, as they don't slip and have an easy pull and great feel.
    Yes, that why I use Wiseco piston, I hate that slapping.

  8. #23
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    Jun 2013
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    Quote Originally Posted by Tecate performance View Post
    I came across a 350x with 500 head on ebay last year. It had the 500 head and rocker cover. For the oiling, there was a 90 degree pipe fitting on top of the head to oil the cam. The guy had taken a couple pics of the rocker cover and head when he had it apart and you could see they drilled into the right cam journal and milled a slot......
    Maybe you could remember the verbiage used, and better time frame on seeing the ebay listing you mentioned where the seller posted several pictures of modified 500 top cover. The reason I say/ask this is recently I read another thread where “Barnett468” (I know he lurks here on the forum) was able to research ebay and find the original posting of the item. No pic’s were available, but the seller’s user’s name is there and a message could be sent to him. He might still have the pic’s to share with us. There’s always going to be interest in this early cylinder head modification and any info helps all those interested.

    Funny how another tidbit of info is learned, although I used a total of 6 head hold down studs, now hearing 4 would work, especially if someone had limited resources and funds.

    "HJ" Click image for larger version. 

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    ’84 YT60
    ’85 350x (423cc) with ’81 XL500 head conversion
    ’83 XR500 (628cc) converted 3 Wheel hybrid
    ’73 CB750 K3 converted 3 Wheel hybrid
    ’86 TRX250R chassis XR650L engine hybrid
    ’89 TRX250R (stock )
    ’90 LT500 Quadzilla
    ’85 FL350 Odysses ( water cooled head )
    Lost (sold) but not forgotten ’80 ATC 110 (205cc on alcohol ) ’83 200x ( 222cc ) ’83 200x ( 185s eng ) ’85 350x ( stock )
    added to the collection recently, (2) '70 US90 Aquarius Blue and '74 ATC90 Daytona Orange

  9. #24
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    Dec 2002
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    I saved the pics from his ebay post, I'll see if I can upload them.

    Mickey, what's different about your new wiseco pistons, I'd like to give them a try. The 92mm JE weighed 320gms and stock is 280 I believe, I'll have to check my notes. The 94mm I ran was 340 gms. Also, do you stock those clutch springs again, I'd like to get a few more sets. Thanks.

  10. #25
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    Quote Originally Posted by Tecate performance View Post
    I saved the pics from his ebay post, I'll see if I can upload them.

    Mickey, what's different about your new wiseco pistons, I'd like to give them a try. The 92mm JE weighed 320gms and stock is 280 I believe, I'll have to check my notes. The 94mm I ran was 340 gms. Also, do you stock those clutch springs again, I'd like to get a few more sets. Thanks.
    Wiseco's have the off set pin, the JE can be made that way for a extra charge. I'm running a 97mm, I want it to rev but my piston is 361 grams, but I like it better then stroking them because when you try to rev them you will break a crank. That's also the reason for running the 5mm valve stems, the stainless steal valve are bigger and weigh less the OEM stockers.. Stock OEM valves are heavy and magnetic , meaning they won't take the RPM's either because they are junk material. Then as I have talked about before to get any compression out of a 500 head you have to have a big dome. Flat top pistons breath better. You guy are looking back as far as building motors, look to the new style stuff.

  11. #26
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    Dec 2002
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    172
    Click image for larger version. 

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ID:	221205 You can see the oil hole here.
    Last edited by Tecate performance; 09-05-2015 at 01:18 PM.

  12. #27
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    Click image for larger version. 

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ID:	221206here you can see one of the studs, so maybe he used them.

  13. #28
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    Click image for larger version. 

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ID:	221207You can see the oil line to the head.

  14. #29
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    Click image for larger version. 

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ID:	221208other side. I guess there's not much detail other than the first pic, but that's all that he posted.

  15. #30
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    Yep, that all works but the head won't flow as good. We were going to flow both heads , but I told the guy with the 500 head no one cares, they are going to do it anyway and they don't care.

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