Frankenstein Honda XL350 Street Tracker Build

Andrew.Y

New Member
Little intro of myself, 22 years old and just finished Automotive Engineering. Just started working on a project this week and thought I'd share some the progress being made. Essentially, this build will start as a XL350, and eventually (Hopefully) turn into a street tracker inspired build.

A few years ago I purchased a 1978 Honda XL350 for $100 (with an off-road ownership) in really rough shape, with the bike very rusted, engine corroded, non-running, and fuel tank heavily dented and leaking. After a carb clean and cleaning the points I was able to get it to run, although oil was coming out to the exhaust. Determined the ring gaps were bad on the compression rings, oil rings were gummed up and had to be replaced. After the rings and gaskets were replaced compression was back to normal and was running as it should. Its been in the garage sitting, and I had acquired XL parts from scrap yards over the years, mainly a good condition XL175 tank, carb, etc.

16144922_811110395708294_45552675_o by Andrew Young, on Flickr
16145790_811110412374959_723315286_o by Andrew Young, on Flickr

Fast forward to this past month I have successfully switched the ownership to On-road after several visits to the Service Ontario. They were reluctant to switch it since they thought it was a dirt bike not meant to be legally on the road. I had contacted Honda Canada and requested an official document stating it was an on-road/off-road motorcycle in Canada meeting all safety and emission requirements at the date of manufacture. Along with a sworn statement, Service Ontario was able to switch the ownership.

Since the original tank that came with the bike was heavily dented and leaking, I decided I would modify the bike to fit the 1973 XL175 tank I had got at the scrap yard, which was pretty good condition after de-rusting the inside and pulling some of the dents out. This week I chopped the rear of the bike off and chopped the front end of the bike at the down tube. A spacer was machined on a lathe and welded at the down tube; this was done to raise the fuel tank higher to clear the top of the engine. The rear of the bike was chopped off to redo the tubing to allow the fuel tank to fit. All the tubing was bent using a tubing bender I made specifically for this project, including the dies which I machined manually on a lathe. Its essentially a JD2 tube bender copy using a ratcheting mechanism.
DSC07824 by Andrew Young, on Flickr
DSC07825 by Andrew Young, on Flickr

The bike with the rear frame chopped off.

DSC07831 by Andrew Young, on Flickr
DSC07829 by Andrew Young, on Flickr
DSC07834 by Andrew Young, on Flickr
DSC07837 by Andrew Young, on Flickr
DSC07839 by Andrew Young, on Flickr

Bends for the rear frame were completed on homemade tubing bender; JD2 copy.

16121584_809373695881964_2036812492_o by Andrew Young, on Flickr
DSC07842 by Andrew Young, on Flickr
DSC07855 by Andrew Young, on Flickr

All the tubing is 7/8" and plugs were machined and welded wherever there is a butt joint. A hole saw mounted in my lathe chuck did a pretty good job of coping the tubing for fish mouth joints.

DSC07844 by Andrew Young, on Flickr

A mount was welded to secure the fuel tank.

DSC07846 by Andrew Young, on Flickr
DSC07854 by Andrew Young, on Flickr
DSC07857 by Andrew Young, on Flickr

All structural welds had been completed (suspension & rear frame), and the current state of the bike is a roller.

DSC07857 by Andrew Young, on Flickr
DSC07859 by Andrew Young, on Flickr

I ordered some parts for the engine and will get the engine running good with a Mikuni VM32 before moving on further in the project. Next steps while waiting for Ebay parts is to:
- Fabricate a seat pan and mounting points on the frame
- Gussets for structural support
- Engine wiring
 
Re: My Attempt at a 1978 Honda XL350 Street Tracker Build

Looking good man. Nice work with the pipe bender. That cross member that holds the upper rear engine mounts looks really tweaked, though?


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Re: My Attempt at a 1978 Honda XL350 Street Tracker Build

Love it. I'm a big fan of the 175 tanks too, minus their lack of volume.
 
Re: My Attempt at a 1978 Honda XL350 Street Tracker Build

advCo said:
Looking good man. Nice work with the pipe bender. That cross member that holds the upper rear engine mounts looks really tweaked, though?


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From stock the rear cross member appears to be not level, but the mounts for the engine are level. I dont know why the design is like that.
 
Re: My Attempt at a 1978 Honda XL350 Street Tracker Build

Interesting. They made a lot of changes to the frame in '75 from the looks of it. I'll be watching though, keep up the good work


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Re: My Attempt at a 1978 Honda XL350 Street Tracker Build

Yesterday I completely tore the engine apart and started cleaning the cases in preparation for eventually painting the engine black. Will need to buy some heli-coils because there are some threads that are stripped on the case. I also ordered a full gasket set and a full oil seal seal set.

DSC07867 by Andrew Young, on Flickr

Two parts I ordered came in the mail; a kick start lever, and the kick starter shaft assembly. Not to happy with the kick lever, sold as brandnew but came and was rusty and seized, had to take it apart and free it up. The only concern is the kick lever seems to be cheaply made; sloppy at the swivel and the splines are poorly manufactured. I fear that my kick starter splines will get damaged if I attempt to install in, it does not slide onto the shaft easily. Does anyone know which kick starters are compatible with the 78 XL350? Ive heard xl250 is interchangeable with xl350?

Started making the seat pan as well. Its gonna sit up flush against the tank. Its fastened to the frame by 1/4" bolts welded to the seat pan, bolted to cross members on the frame. What is the best way to upholster these metal pans? I was thinking maybe drill the whole perimeter for 3/16" rivets, then rivet the vinyl or leather on? Also need to find a place that sells foam.

DSC07863 by Andrew Young, on Flickr

DSC07862 by Andrew Young, on Flickr

As it stands now. Still need to finish the pan; need to weld some roundstock around the edge so the vinyl/leather doesn't get cut on the edge. Next is to make a little box to go under the seat to house all wiring for the bike. Does anyone have experience using 12 volts on this bike? Do I need to rewind or can I switch the reg/rectifier?

DSC07875 by Andrew Young, on Flickr

DSC07874 by Andrew Young, on Flickr

DSC07873 by Andrew Young, on Flickr
 
Re: My Attempt at a 1978 Honda XL350 Street Tracker Build

irk miller said:
Love it. I'm a big fan of the 175 tanks too, minus their lack of volume.

I really like how slim the tank is in comparison to the 350 stock tank. I believe its 7 liters, which should be fine...I hope...
 
Re: My Attempt at a 1978 Honda XL350 Street Tracker Build

For seat foam, I used a seat cushion from Menard's. It is about 2" thick and only $5 each.

http://www.menards.com/main/outdoors/outdoor-recreation/hunting-equipment/treestands-blinds/guidesman-13-x-14-hunting-seat-cushion/p-1444421318549-c-13885.htm?tid=1768455149664530795&bargainStoreId=3320

I've ridden for a couple hours at a time with no issues. Pretty comfortable.
 
Re: My Attempt at a 1978 Honda XL350 Street Tracker Build

Today I did some more cleaning of engine internals. The transmission is only semi assembled right now until the gaskets and oil seals arrive in the mail although it does seem to shift good now, I was having trouble finding neutral. Also spent alot of time cleaning the cylinder; those damn fins are so hard to clean. De-greaser, solvents, and soap wouldn't remove some of the build up between the fins so I used brass wire brushes on a drill and a Dremel. After it was cleaned, it was honed and I used a file and a die grinder to flatten the end of each fin. I then painted the cylinder using VHT high temp paint. Once fully cured, Ill sand the edges of each fin to reveal the aluminum.

I plan to move onto painting other engine components, specifically the case. Still kinda unsure if I want a fully blacked out engine or some small parts to be polished.

I found a Mikuni VM36 Kit that XLint Performance sells for the XL350 for $295. It comes fully jetted and with the throttle and cables. I might buy that for the convenience, although I could save alot of money if I can find the right combination of jets to use for a 350. All the Mikunis on Kijiji right now are the VM32 which are going for about $50. Just need to buy the right jets/needles, which Ill need to do some research on since Ive never had any experience with Mikuni's

DSC07891 by Andrew Young, on Flickr
DSC07880 by Andrew Young, on Flickr
DSC07879 by Andrew Young, on Flickr
DSC07877 by Andrew Young, on Flickr
DSC07882 by Andrew Young, on Flickr
 
The gasket set arrived this afternoon. Also painted the bottom case. I'm expecting the oil seals to arrive tomorrow, if so I'll assemble the bottom end. Next I'll be moving onto the head, rebuilding (valve seals, valve lap) and painting along with the points and advancer mechanism.

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Be sure to have a machine shop check the valves, the valves on these motors were prone to bending. Check here for engine parts:

http://xlintperformance.com/index.php/parts/87-engineparts.html
 
advCo said:
Be sure to have a machine shop check the valves, the valves on these motors were prone to bending. Check here for engine parts:

http://xlintperformance.com/index.php/parts/87-engineparts.html

Ill see if I can check them by chucking them in my lathe and running a dial indicator on the valves. I had emailed xlint but they have yet to respond. Did you ever end up using a Mikuni on your bike?
 
Andrew.Y said:
Ill see if I can check them by chucking them in my lathe and running a dial indicator on the valves. I had emailed xlint but they have yet to respond. Did you ever end up using a Mikuni on your bike?

Yeah you can check them with a dial indicator. Best way to get in touch with XLint is by phone. The guy who owns it is very helpful and knows a lot about these motors.

I am using the stock Keihin right now, but I may upgrade to a Mikuni down the road. I think irk is using a Mikuni on his 250, and I know CXman is using one on his 350 with a 418 kit in it.
 
advCo said:
Yeah you can check them with a dial indicator. Best way to get in touch with XLint is by phone. The guy who owns it is very helpful and knows a lot about these motors.

I am using the stock Keihin right now, but I may upgrade to a Mikuni down the road. I think irk is using a Mikuni on his 250, and I know CXman is using one on his 350 with a 418 kit in it.
Sounds great, I'll definitely have to give him a call

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Was having so much trouble cleaning the head, between all the fins and the baked on mud and oil. Decided to bring it to a soda blasting company nearby. Should get it back in a weeks time, but no rush since I'm waiting on a cam chain tensioner guide from eBay. Once I get that I should be good to bolt the engine back together.

Was looking further into the Mikuni's. The stock spigot mounting diameter of the stock Keihin is ~40mm; the VM 32 and 34 have the same diameter of 40mm. However I see alot of people using the VM36 on their builds which has a slightly larger diameter of 43mm. Will the VM36 squeeze into the stock carb boot? Seems like it would be a very tight fit, no?

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