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Just picked up an HL500 project - Planning on restoring it

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New this Forum, but have been around some other motorcycles forums for a couple years.

 

I was fortunate enough to find what I think is an original Hallman/Profab HL500 over the weekend. It's been tough finding information on these bikes. For instance I have only seen one photo of my style of swing arm that has interesting dual shock mounts, one in the middle of the arm and one by the axle.

 

 
 
What I got:
 
HL500 frame and Swingarm (with all mounts included)
The original unstamped TT500 Motor with a 540 kit. (frozen from being left outdoors)
YZ125 Aluminum Gas tank with TT decals
1977 TT500 mostly complete minus seat and airbox (turns over with compression)
 
 
Here are some photos 
 
image3_zps921802df.jpg
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IMG_7161_zpsy3oadmgj.jpg
 
 
Mototek Ignition and no serial number.
 
image6_zps66a20038.jpg
image5_zps2eb1ec70.jpg
 
 
What I found in the top end :(
 
image7_zps250d8bf8.jpg
image8_zps987796c9.jpg
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image13_zpse5ff010a.jpg
 
 
Finding information on these has been pretty difficult, but Rob Phillips at Husky Restoration has been extremely helpful so far.
 
 
I am dropping all my other projects to work on this. Wish me luck!
 

 

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The head has been ported by someone with skill, but it looks like an early head with a 45mm I-valve. I would not waste time on any head with smaller than a 47mm I -valve and preferably larger to 49mm. The small valve heads choke early and the motors quickly fade above 6000 rpm even with porting. The cam is a Megacycle 25140. Most consider it to fit the old 3/4 race cam definition. Again, would not be my choice but can be sold if there is no scuffing. It is popular for street use with the SR500 and 400 crowd. The mototek CDI is long out of production, there are few if any parts and they were not that great to start with. (PVL is popular today) The Wiseco "soup-can" piston is heavy, the rings are far down the side and they were made from a lower quality silicone aluminum material compared to current offerings from Wiseco and others. 

The SR500 forum is the place for info on the Yamaha 500 (SR500Forum.com). Lots of old racers and experience there. These motors are still being race in VMX, Road race singles and flattrack. Parts are getting expensive but good deals can still be found if you are patient and determined.

Your Profab frame and swingarm are true gold! Treat them well. The 125 tank has value also. The parts bike will come in handy, it looks like it has a big valve head.

Edited by pcnsd
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The head has been ported by someone with skill, but it looks like an early head with a 45mm I-valve. I would not waste time on any head with smaller than a 47mm I -valve and preferably larger to 49mm. The small valve heads choke early and the motors quickly fade above 6000 rpm even with porting. The cam is a Megacycle 25140. Most consider it to fit the old 3/4 race cam definition. Again, would not be my choice but can be sold if there is no scuffing. It is popular for street use with the SR500 and 400 crowd. The mototek CDI is long out of production, there are few if any parts and they were not that great to start with. (PVL is popular today) The Wiseco "soup-can" piston is heavy, the rings are far down the side and they were made from a lower quality silicone aluminum material compared to current offerings from Wiseco and others. 

The SR500 forum is the place for info on the Yamaha 500 (SR500Forum.com). Lots of old racers and experience there. These motors are still being race in VMX, Road race singles and flattrack. Parts are getting expensive but good deals can still be found if you are patient and determined.

Your Profab frame and swingarm are true gold! Treat them well. The 125 tank has value also. The parts bike will come in handy, it looks like it has a big valve head.

 

I was thinking about trying to keep it as original as possible when restoring it. I don't think SR heads were available yet were they? As for the rest of the motor I'm not 100% sure what I will do yet. I am a 2-stroke guy, so things like Camshafts, valves and such are fairly new to me. My friend is selling me a YZ400 for parts like the forks and wheels.

 

I have been having a hard time trying to find  my swing arm, and this is the only photo I have been able to find.

 

http://classicyams.com/special-yamaha-bikes/special-yamaha-bikes/yamaha-hl500-sten-lundin-works-bike.html

 

hl500rhlarge.jpg

hl500lhlarge.jpg

 

 

Good Luck!! Lots of work there!!  Show finsh Photos to!!

 

Thanks, I'll be sure to post some photos as I work on it.

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The big valve head became available from Yamaha in 78. They were just following what the head porters were already doing (Adding valve size and fin area). The Profab frames were based on the original Hallman design and included use of two shock mount position choices. It was during a time a rapid suspension development and change (Late 70's). Not everyone agreed on what was best and many concepts were later abandoned as the Techno flavor of the month. (17" MX wheels, 36mm forks with 12" travel, under damped Yamahoppers, many others.) When bikes went to long travel it took awhile for the valving and design technology to catch up.

The early HL's ran a 17.5" shock at the rear mount, the later ran a 16" shock at the forward mount. The 16" shock is now considered to be the better choice.

The YZ400 will be a good fit for wheels and brakes, I will suggest looking for the later YZ465 forks. They are 2mm larger in diameter and will be stiffer for a heavy machine. You will need to have a cable made for the rear brake set up, Terry cable used to be the source.

Edited by pcnsd
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Keep us posted with this project.  A motocross play bike based on a Thumper would be the bomb.   

Edited by Jimmy Pascol

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The big valve head became available from Yamaha in 78. They were just following what the head porters were already doing (Adding valve size and fin area). The Profab frames were based on the original Hallman design and included use of two shock mount position choices. It was during a time a rapid suspension development and change (Late 70's). Not everyone agreed on what was best and many concepts were later abandoned as the Techno flavor of the month. (17" MX wheels, 36mm forks with 12" travel, under damped Yamahoppers, many others.) When bikes went to long travel it took awhile for the valving and design technology to catch up.

The early HL's ran a 17.5" shock at the rear mount, the later ran a 16" shock at the forward mount. The 16" shock is now considered to be the better choice.

The YZ400 will be a good fit for wheels and brakes, I will suggest looking for the later YZ465 forks. They are 2mm larger in diameter and will be stiffer for a heavy machine. You will need to have a cable made for the rear brake set up, Terry cable used to be the source.

 

 

Thanks for the help. You mentioned in your first post that it looked like it had been ported by someone with skill, how can you tell? You also mentioned the parts bike looks like it has a big valve head, and again I am wondering what tells you that?

 

Like I said 4-strokes are new to me, and I am learning all I can.

 

Keep us posted with this project.  A motocross play bike based on a Thumper would be the bomb.   

 

 

Don't worry I'll post lots of photos, and updates  :thumbsup:

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Thanks for the help. 1. You mentioned in your first post that it looked like it had been ported by someone with skill, how can you tell? 2. You also mentioned the parts bike looks like it has a big valve head, and again I am wondering what tells you that?

 

1. I have owned an even dozen performance 500's, at least one continuously since 1978 and currently own three. I have the 500 sickness. I race them and I have my own flow bench. I can tell the porter was skilled because they didn't screw it up which is easy to do. None the less, that won't spare you the short falls of a too small I-valve.

 

2. The big valve head has more fin area. If you have the sickness, they just stick out to you.

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pcnsd certainly seems to knows his stuff on these.  I have read a little bit on them not a whole lot but I think there are possibly thecoolest dirt bikes ever built. They just simply look badass!!

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1. I have owned an even dozen performance 500's, at least one continuously since 1978 and currently own three. I have the 500 sickness. I race them and I have my own flow bench. I can tell the porter was skilled because they didn't screw it up which is easy to do. None the less, that won't spare you the short falls of a too small I-valve.

 

2. The big valve head has more fin area. If you have the sickness, they just stick out to you.

 

 

Got it. Good to know. I have had a few TT500's, but never did much with them. Also I picked up a TT the day before picking up the HL. It runs great, but it looks like it just has a standard head.

 

image1_zpsa2d8f335.jpg

 

Here is a photo of all of them in my garage

 

FullSizeRender_zpse40cd9f1.jpg

 

pcnsd certainly seems to knows his stuff on these.  I have read a little bit on them not a whole lot but I think there are possibly thecoolest dirt bikes ever built. They just simply look badass!!

yes he does! And I have to agree, I have not seen a cooler looking thumper.

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I picked up a couple goodies for the bike this weekend.

 

Bought a YZ400 parts bike, to steal the Front end and Wheels.

 

I also stumbled upon a pair of 17" Fox Air Shocks, in a storage container in the middle of nowhere.

 

image6_zpsbc10f84f.jpg

 

I still need to find a '76 YZ125C seat. I also need to figure out a pipe for the bike.

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You may have a  'Geoff Morris Concepts' frame, he makes pipes and other goodies too... Looks like he out of stock on most items, but if you reach out to him he may build you a pipe.

 

http://www.geoffmorrisconcepts.com/23/online-shop/29-Yamaha-Hl-500-Replica-Frame-Kit

 

I talked to Geoff, he told me I have an early Pro-Fab frame. I'll have to contact him about pipes and side covers, when I get some more money in.

 

I just picked up a pair of Simons forks last night for the bike.

 

I'll be sending them out to be refurbished on Monday, I already sent my Fox Air Shocks out to get the "works" treatment.

 

FullSizeRender_zps5d067f32.jpg

Edited by Mr_Dunev

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