Offroad big block buggy

Edwin Spangler

Well-known member
Messages
844
Reaction score
813
Let me see a picture of the master as it is now. One of those, 2 front, 1 rear output masters?
 

Edwin Spangler

Well-known member
Messages
844
Reaction score
813
Ok I thought it was a different version but no matter, my response is pretty much the same. I bought that same one for my 4 wheeler.

1. It doesnt work well no matter what I do. If I hop on the pedal on one foot, I can get the wheels to lock for a fraction of a second.

2. I bled them with a vacuum first, then I got some pressure in the line and cracked the banjo bolt. Thats when the bubbles really came out. Obviously you need to be extra cautious doing this, much easier to suck air in this way.

3. You *might* need to adjust the (thrust clip?) and put some preload on it.
 

Attachments

  • bandicam 2025-06-18 07-48-51-263.jpg
    bandicam 2025-06-18 07-48-51-263.jpg
    57.4 KB · Views: 0

Eztrail

Well-known member
Messages
257
Reaction score
417
Location
Cleburne, Tx
Lost the cup to my mini mighty vack bleeder, so picked up a different one from harbor freight today. Will see how it goes, it gets loaded on the trailer tonight regardless.
 

Eztrail

Well-known member
Messages
257
Reaction score
417
Location
Cleburne, Tx
I had left the kart jacked up all night. When I got home I bled the brakes a couple times and got some good air out on the first try. Each of the following trys yielded no more air. Didn't have time to vacuum bleed.
 

Eztrail

Well-known member
Messages
257
Reaction score
417
Location
Cleburne, Tx
Started hitting the trails the other day. 21 mile ride. Carb is rich so I ordered some more main jets. Went for another ride today and this happened. 20250623_115823.jpg
1" pillowblocks. Was only a 7 mile tow back to our cabin. And we had 2 spare pillow blocks. Hope tomorrow's ride goes well.
20250622_135808.jpg
 

Denny

Canned Monster
Messages
11,653
Reaction score
8,093
Location
Mayberry, Indiana
Started hitting the trails the other day. 21 mile ride. Carb is rich so I ordered some more main jets. Went for another ride today and this happened. View attachment 154689
1" pillowblocks. Was only a 7 mile tow back to our cabin. And we had 2 spare pillow blocks. Hope tomorrow's ride goes well.
View attachment 154690
That was not good. Hope it’s going better now.
 

Eztrail

Well-known member
Messages
257
Reaction score
417
Location
Cleburne, Tx
Well we got it all put together and went out today for another ride. Then about 10 miles in.....20250624_142621.jpg
The tow of shame.
20250624_143303.jpg
The 3/4" jackshaft the driven is on sheared in half. That jackshaft is 14" long and supported by 3 pillowblocks. 20250624_191834.jpg
When my 1" pillow blocked broke in half the other day I was doing some donuts in a large dirt area. We think because of a messed up link of chain a rock got kicked up and lodged between the sprocket and chain. Now with this today I think this jackshaft was severely compromised and just finally let loose.
 

Eztrail

Well-known member
Messages
257
Reaction score
417
Location
Cleburne, Tx
Not really happy with the performance of the motor. I know the carb was still too rich but don't think tuning would get me as far as I want. Debating leaving this motor on or a v twin. So in the meantime I pulled the head last night. Cc'd my head, I was at 32cc and 9.4-1 compression. I was able to shave about .015 off the head. And change from a .045 head gasket to a .027. That got me up to 10.1-1. We'll see how that performs. I know it wont be a big difference.
Also on the table is the possibility of some 1.2 ratio rockers. I called NR Racing and they said the 1.2 rockers would work well with my cam.
 

panchothedog

Well-known member
Messages
2,788
Reaction score
3,743
In your very first post you mention that the engine is a stage 2 440 duro - max.
Not exactly sure what that describes. Slide carburater and header pipe for sure. When you had the head off did you notice if it had a dished piston ( as most of the non hemi versions do?) A flat top piston would eliminate about 18 cc's of combustion chamber volume on a big block. Is the governor still in the engine?
If you have already contacted N R Racing, you must be aware of the enormous amount of aftermarket speed parts available. Master Hack ( A regular on this forum ) built his Honda 390 using their parts and advice, and while I am sure he didn't triple the stock horsepower, he easily more than doubled it. A nicely warmed up big block is a pretty serious engine for a buggy your size.
A V Twin is going to be very heavy, purchased new, quite expensive, and if left in the stock governed state, while adding more torque, will still be disappointing once it reaches it's 3600 governed rpm and quits pulling.
 

Eztrail

Well-known member
Messages
257
Reaction score
417
Location
Cleburne, Tx
So I installed this engine in a Chinese version of a brister chuck wagon. With a yamaha golfcart rear end. I used NR Racing 280-0211 torque cam. Stock dished piston. Deleted the governor, cut to length pushrods, Mikuni tm32 flat slide carb and a small cheerybomb type muffler. Worked very well in the machine.
I even Went to several offroad parks with some friends. When friends wanted to step up the riding locations to areas with bigger hills I knew I needed a change.
I then yanked the 440 and bought a new predator 670. That motor got a Mikuni 32mm flat slide, governor delete, and exhaust. Used that setup for a short time before I sold it. (There was a gx620 in there at 1 point but that was the biggest piece of crap I ever worked on.)
All this to say i am familiar with my options. The extra weight of the v twin is quickly offset by the extra torque. Spring kits can be had for extra rpms, and because of the massive torque, you can change ratio to attain the same top speed but not rev the twin as high.
Can't decide between a predator 670 new that I break in and maintain, or a used briggs vangaurd with 200+ hrs and an unknown maintenance history.
But for now I'm going to collect parts to convert from a swing arm to irs. Ill keep everyone updated.
 

Hellion

Moderator
Messages
8,603
Reaction score
3,683
Spray tip clogged up. Last 4 different spray cans have all clogged up on me.

Happened to me with the semi-gloss black Rustoleum tall cans with "25% MORE" or whatever on it. I contacted them and made them send me a dozen new caps for free but they insisted all along that I was wrong. I follow the directions on the cans to the letter.

Figure it's due to their newer 2X paint formulation (and high volume nozzles) where they're making you cover everything in one pass instead of the finer misting nozzles that allowed you to build up thin layers with ease.
 

panchothedog

Well-known member
Messages
2,788
Reaction score
3,743
Well Eztrail, sounds like you have researched your engine options better than I might have thought. Good for you. One GLARING mistake I made in post # 113.
A flat top piston is worth about the same as milling the head .018", as far as combustion chamber volume is concerned. A lot less than 18cc's. Late at night and old age are starting to not mix well.
 

Eztrail

Well-known member
Messages
257
Reaction score
417
Location
Cleburne, Tx
All good, just glad there are still people here.
Right now I'm at 10.1-1. I could get more with flat top. But I'm near the safe limit for 87 octane. I run 89 ethanol free and I like having that buffer zone here in the Texas heat.
 
Top