Hiusun engine mods
- Thread starter Tarslave
- Start date
What's your goal and budget? Have you ever worked on one of these engines before? Big tire or small tire bike?
You could do a stage 1 setup that's just an air filter, header and carb rejet or go balls out with the billet parts, big cam, big valve head, big Mikuni carb, roller rockers, etc.... A stage 1 setup should run you under $100, while going with an all out build will cost in the thousands.
If you have one of the big tire Coleman bikes, a stage 1 setup with a torque converter will probably be the best bang for your buck.
You could do a stage 1 setup that's just an air filter, header and carb rejet or go balls out with the billet parts, big cam, big valve head, big Mikuni carb, roller rockers, etc.... A stage 1 setup should run you under $100, while going with an all out build will cost in the thousands.
If you have one of the big tire Coleman bikes, a stage 1 setup with a torque converter will probably be the best bang for your buck.
Just the head and valvetrain on my stage 4 212 build was around $1100. These engines get expensive to build if looking for a lot of power. I'm going to be building a 236 stroker engine for my drag frame that will be replacing the 212. The bike does 70+, but I want to do over 80 with it in the 1/4 mile.
Check out these sites for parts.
www.studzracing.com
www.nrracing.com
www.childishconcepts.com
www.eccarburetors.com
www.dynocams.com
www.paulskarts.com
www.kartcityperformance.com
www.bmikarts.com
Check out these sites for parts.
www.studzracing.com
www.nrracing.com
www.childishconcepts.com
www.eccarburetors.com
www.dynocams.com
www.paulskarts.com
www.kartcityperformance.com
www.bmikarts.com
OldMiniBikes is a good site, NR racing good site, Smallenginecams good site. Lots of others but those I have delt with. What is your level of competence in building one of these engines? Do you know how to pick a cam, evaluate required head flow, set clearances and check bore straightness? Or are you mechanically inclined and just want to bolt together a bunch of parts, check critical clearances and call it a day. Full on internal upgrades does not explain exactly what your thinking. I have never seen a hisun but assume it is a honda gx200 clone. What flywheel taper does it require? What rod Pred/honda clone, what gaskets fit it etc.
Eager to lean, I’ve never built a motor. Figured I’d start with a small engine. I’m a construction work, (paving specifically) . This is a new hobby to be. I have two 200ctu minibikes. One mine, one my fiancé. I’d like to build one. They already have a stage one with torque converter. I’m interested to go further. I’m mechanically inclined.. sorta, looking to get better, starting small. I’ve lifted a wrangler, slapped a 350 small block in a blazer. I wanna make this bike nasty!! I’ll do research and I’m sure eventually know everything u are talking about, hopefully I like th if s site abs already been learning quite a bit. I slow way down with work in the winter. Wanna try. I’m eager to learn.
Here is a link to a HF predator engine build you can look thru and see what goes into building one of these for hi performance use. There are a number of folks that have provided step by step directions here but its not always easy to find.
Building a non hemi predator Test Motor | OldMiniBikes.com
Building a non hemi predator Test Motor | OldMiniBikes.com
Besides engine mods you may want to get a good understanding of gearing. Even with a stock engine the Coleman 200's can use better gearing when a torque converter is installed in my opinion. Once the belt shifts it's running a 4.5:1 final ratio. It works but is not good from a performance perspective.
I'll never run stock gearing on my Coleman's with a torque converter, stock engine or not.
I'll never run stock gearing on my Coleman's with a torque converter, stock engine or not.
I assume you are road riding at those speeds. Would be more fun with a 60 tooth but aren't you still running the stock main jet in the carb? With a 60 tooth you'll top out at a higher RPM (4300 ish). With the stock jet it will be running really lean at that RPM. You may have the carb with the non removeable jet. Some clever guys have gotten it out. Others just buy a new carb. Use a 36 jet, air filter kit, and header pipe.
My bikes are off road only and never see more than around 35 mph. If I put a TAV on my stock bike I would get a 60 tooth and a longer chain. There's more low end and the RPM is in a slightly better range when the belt shifts.
My bike with a TAV has 9/60 tooth gearing. Works well off road. Engine has a billet rod and PVL flywheel so there would be no concerns about running higher RPM if I ever put it on the road.
My bikes are off road only and never see more than around 35 mph. If I put a TAV on my stock bike I would get a 60 tooth and a longer chain. There's more low end and the RPM is in a slightly better range when the belt shifts.
My bike with a TAV has 9/60 tooth gearing. Works well off road. Engine has a billet rod and PVL flywheel so there would be no concerns about running higher RPM if I ever put it on the road.
OK so I managed to get a reverse drill bit on the factory jet. I got it out. Now she’s running a little strange at the low range. Right when I start to get on her she spits and sputters but me and once it kicks in it has a lot better acceleration with a .036 on it. Wondering why it’s sputtering like that. Used the emotion tube that came with the .036 jet and took the factory one out. Is this just a matter of plug and play? Trying different jets and Tubes. The ones I put in Had visibly larger hole. Runs great other than the sputtering in the low end of the throttle.. also , Now it starts without the choke. Usually first pull. I’ll write it around a little bit maybe pull The bowl off again make sure the jet is all the way in. But if it doesn’t clear up I Do have the other carb but I just bought. Any reason why you think it’s sputtering in the lower end?
Aahhh I see, kinda bummed a little cuz the factory one was good, but was running a little lean with the air filter and header. Also this .036 definitely increased my acceleration a little. So I’m gonna try a .038. There’s a .036 in it now.. does the emulsion tube have to coincide with h the jet size? The factory one had more holes in it, but the one that came with my .036 jet, hat a larger hole in the bottom and top. Honestly it’s running ok, just stumbles a little at low throttle, wakes right up after that. Maybe a different plug? Thanks for the response I truly value u guys, what a gift u guys are all your knowledge.