Mr.modified's GTR Four Zero

Yeah. Do you have a rolling chassis yet

Not yet, very close. Painting A arms this afternoon. Briggs and stratton decal set ordered.

Fan shroud base and A-arms painted and ready to go.


Fan shroud. Came out ok, but I had an issue with the spray can which messed up the upper cylinder side. No time to bother with it, still a lot to fabricate on this thing. Specks of dried paint in the can or something. Not sure if the spray cans are bad to start with or if it just messes them up when you try using a half used can.


New grease fittings installed in A-arm spindles.


Header mostly done. Just need do decide if the entire system will be one piece or if it will have a flange. Then what kind of flange, either flexible ball/spring type connection or just a regular washer flange. That's why I didn't make a collector yet.

Nice work on the header. Are you going to paint it white, like an old street rod?

Thanks. I think I'm going to paint the whole exhaust system black. I'm trying not to get too fancy with colors and things because I want to keep everything with a more factory look vs. a hot rod. Everything clean, but some rough edges here and there for the hand built race car feel....lol

A-arms look good. The white is quite sharp! Any ideas on the final colour of the bodywork?

should build custom headers like that and sell them i could be the first buyer lol

Body will most likely be white also with light grey frame and rims. Not 100% sure about decals or stripes ect, but I'll probably come up with something.

It would be neat to sell exhaust pipes for this stuff if you could make them a little quicker and cheaper. I don't have a good way to bend the pipe where I want it so I have to buy those 90 degree bends for about $6 each. Was a bit easier this time to make the pipe since I could weld it while it was still bolted onto the junk test engine. Normally I have to try to not mess up the engine I'm going to use.

So last Thursday-Sat i went to Mr.Mods house for another deal... But stayed long to work on junk.

Some behind the scenes of the place... little late on pictures but whatever

Welding something


Juek block ready to go together, with high quality footage of installation.



We did a few things. Go to the shop. Pet some animals. Drive pretty much everything thats street legal and then some. Get tought how to drive 5 speed better from the driving school of mr.modified is heavy, angry, irritate jersy traffic. Cleaned a carb on a mini bike that i really wanted to ride. Watch some rally videos. Go eat food. Junk some tires. Look at the places down there, much different from where i was.

4 hour drive wasnt that bad, all interstate stuff.

Didn't notice but are you going to use a billet flywheel for sake of weight/quicker revs.

That top picture is me welding up the custom oil fill plug.

As for a billet flywheel, I weighed the stock flywheel and got about 18 lbs. I checked the weight on the ARC website on their billet flywheel and they also list 18 lbs. So the only advantage would be the adjustable ignition timing and of course the added safety factor. I'm going to just use the stock flywheel. I removed the ring gear to save some weight without altering the flywheel. I think to keep the stock engine together I'm going to "try" to be half way easy on it, at least as far as high rpm's go. I put one cylinder head on today, tommorrow should see the rest of the engine assembled and some work on the manifolds.

Copper high heat permatex applied to the head. Snugged the bolts down easy then waited an hour before torquing the bolts to 15 ft lbs. Heads are mostly stock except for a small area on the one side that I took some material out and smoothed out the edge. The idea was to encourage swirl in the combustion chamber judging by carbon deposits on the head before I cleaned it. Who knows if it will change anything, I'll check what the heads look like after the engine has some run time on it.


As stated by redline, I'm putting a video together of the engine assembly more or less and will probably have some test run footage on there. Hopefully soon.

I thought you were going to change the location of the spark plug hole, what happened to that?

I thought most of the point of the billet flywheels that they were lighter.

Yes I was planning on changing the spark plug location, but a decision was made at GTR HQ to concentrait on the rest of the machine first. The experimental heads are time consuming to make and I don't have a good way to get a flat surface for the plug gasket to seal against. With the amount of other things that still need to be done in the next couple months, I can't afford to play around with the heads that much. Later If I have time, I might try the other heads. And with the flywheel, I figured the billet one would be at least somewhat lighter too.

Ah right. I suppose it wouldn't change much. Can't wait to see her running!

NEW TIRES HAVE ARRIVED! The old tires I was going to use to the left of course. Side walls had a lot of dry rot, so I figured I should just start fresh. Just have to sand blast the rims and start mounting them.


The new tires are carlisle turf masters, the conventional looking tread called turf savers. New tires are supposed to be a bit heavier, 4 ply instead of two. Tread looks kinda neat, a little more aggressive and deeper tread than regular turf savers. The old ones might be worn down some too.


Here's where we are with the dual carbs and exhaust. I have everything bolted onto the test block so I can try to figure out the throttle and choke linkage nightmare. I have an idea, just have to weld some more junk onto the intakes.


I replaced the press in fuel inlet on the left carb so that it was facing down like the other carb. I think the fuel lines will come up between the exhaust pipes. The upper cylinder on the left will be towards the front of the machine. Throttle cable will probably start at the right carb, wrap around the back of the engine, and connect to a foot pedal on the far side of the engine...at least that's what I'm thinking right now.

Cool tires! I have used turf masters on the front of my Westwood and they are quite good for being turfs! More aggressive than turf savers. What size? Same size all round I'm guessing

Thanks, yeah same size on all four. I think they are 15 x 6.00 x 6. Still too hot to paint the engine block. I've had trouble with black paint turning grey in high humidity, so I'm trying to wait for a good day. I also found some semi clear plastic/rubber to use for mud flaps.

your luckey that it turns grey I have a problem with it turning blue

Never turned blue for me. Just gets lighter colored. At any rate, I finally painted the block today. I'm think it came out ok for the most part. Tried to make sure I got decent coverage of the fins.

I used duplicolor engine paint I think. Was a little windy out and it caused some spots to look a little dry. Close enough though, you won't see most of it anyway.


Just have the manifolds and the valve covers to paint.

Looking good! Was it brushed on or sprayed on?

How long until first start-up?

I sprayed it on. Tough to give an accurate estimate on the first test run, but I hopefully not more than a week or so. Pretty much have the header done as of today. All that's left to test it really is to finish the intake manifolds and linkages. Also I need to fab up a pull starter. Tonight I need to Put the charging coil, flywheel, and tin work on. I have about two or three ignition coils to try. I'll put on the one that looks best and if I have too much trouble, I'll just buy a new one. I'll post some pics of today's progress later.

One of the front rims. Holes drilled, sandblasted down to bare steel, primed, and painted machinery grey.


First tire mounted, tubeless.


Header 90% done. Test fitting on the frame. Ball socket connection from snowmobile exhaust.


As seen from the top. The aluminum 1" square tube will be what the engine sits on. Foot pegs will need to be in about the same location. Maybe it will double as the foot pegs. Exhaust will need a heat shield to protect your leg for about a 1 foot long section.


One mounting bolt will probably be through the frame. The rest will only be bolted to the aluminum cross members. Crankshaft centerline will be off set from the frame a couple inches.


Other news/design changes:
-I checked again on billet flywheel weight on the ARC racing website. Although I was sure that the opposed twin billet flywheel weight was listed at 18lbs (same as stock), it seems now they list it at only 8lbs. Most likely I read it wrong before. But still, can't afford a $300 flywheel for a junkyard engine.

-Figuring out gearing right now. Current thoughts are gearing for somewhere between 35 and 40mph at 4000rpm

-Ordered a regular go kart brake band to replace the idea of using a rubber serpentine belt. Still going to use my same 4.5" drum which is a water pump pulley from something. Might have been a honda.

Great! On the pictures for the front rims, one of the bolt holes doesn't look centred? Maybe it's just the picture

Thanks. About the lug holes, the center hole is off a lot on this rim. The other front rim is better. The lug holes are almost where they should be though, so it doesn't really hurt anything, just looks bad. I had a tough time drilling the centers out with my mini drill press and a hole saw. I didn't have a good way to hold the rim down so I used ratchet straps to hold the rim to the table. Also the drill press has some play to it, so things jumped around a bit.

Bought gears for the axle, output of the transmission, and a pulley with 1" hub for the crankshaft. If my figures are correct, top speed at 4000rpm should be around 40mph.

Also some stickers I received a week or so ago.