my hf 99 mtb build thread, FINALY!

[young grease monkey]

ok so i got the engine and my frame is back from the welder. It's a real tight fit, so i think i will go near verticle, about 70 degrees. do i use the same amount of oil? now all i need is to make a new intake and some patterns for casting the engine mount. i hope i can use investment casting to make a new manifold, otherwise i will have to use up another favor from my dad's custom fabricator friend. sooo in the next few days i will have the engine mounts ready to be cast and then have the frame sand blasted and powder coated black. sorry no pics right now, don't have time to figure out how to post 'em. gotta get some sleep.

 

[young grease monkey]

so... if you haven't read my other threads that i posted to help plan this thing out, i'm going to use a homemade jackshaft using some sort of a bearing hub and a belt primary drive and a tensioner on the belt to act as a clutch. then i might get a variable pulley from mcmaster carr or ebay so i can change the gear ratio easily for riding around town with tons of torque or higher speed, efficient cruising. also going to order the grubee axle/hub once i sell a lawnmower and r/c car, should get me about $250 to play with! maybe a nice double wall rim if i can get one cheap.

 

[wayne z]

Good question about the oil amount. I would try this:

Put a hose barb fitting in the drain hole with a foot or more of clear tubing on it.

Place the engine on a level surface, and tie the tubing pointing vertical ,and close to the PTO shaft.
Fill the engine to the correct level with oil. You will then see the oil level of the engine in the tubing "sight glass". Measure the distance the oil level is from the bottom of the PTO shaft.
Then mount your engine on the bike, and use the sight glass to fill the engine to the same measurement as before.
Then I would try to fab a dipstick on the oil fill plug, or just a bent wire to stick in there when the fill plug is out, to be able to detect the oil level. Re install the drain plug.

 

[young grease monkey]

Good idea, thanks! I will have to have a 90 degree fitting on the drain hole anyway, because it is so close to the frame. I'm gonna go start the mount now, and I'll take pictures for sure.

 

[tigmaster]

Sounds like a great start Youngin'! I cant wait to see the mount Your going to build!....I was thinking about using the Lil' 99 in the same position on a Board tracker build....Tigmaster....

 

[young grease monkey]

Hmmm it seems there's a problem... I'm torn on what position to mount. Do I need to leave room in front of the seat tube for the jackshaft? I can't mount it vertical if I need a lot of space for the Jack shaft, it will need to be farther up near the headset and with the cylinder closer to horizontal. Aaaaahhhhh!!!! I can't really solve it till I get the bearing hub, which could be tomorrow if I sell my lawnmower today. At least I started the mount blocks, the parts that will bolt to the frame. Nothing to see really, they look like wider, taller versions of the rear mount blocks on HTs. Except made out of styrofoam. I will be using 8mm studs throughout the mount. Broke way too many 6mm studs on my ht. One more thing, would it be a good idea to use an NT speed carb instead of the stock? It wouldn't be hard to fit a manifold to the 99, and my main concern is the throttle on the stock carb. It will be very complex when I have to make an offset manifold and rig up a throttle, but I have a sbp throttle assembly for the NT. but I'm worried about the performance of the NT. The predy carb is decent quality, but the NT isn't so much. The NT is more tunable, and bigger. I guess I will have to figure out the carb situation once I settle on a mount position.

 

[wayne z]

Hmmm it seems there's a problem... I'm torn on what position to mount. Do I need to leave room in front of the seat tube for the jackshaft? I can't mount it vertical if I need a lot of space for the Jack shaft, it will need to be farther up near the headset and with the cylinder closer to horizontal. Aaaaahhhhh!!!! I can't really solve it till I get the bearing hub, which could be tomorrow if I sell my lawnmower today. At least I started to mount blocks, the parts that will bolt to the frame. Nothing to see really, they look like wider, taller versions of the rear mount blocks on HTs. Except made out of styrofoam. I will be using 8mm studs throughout the mount. Broke way too many 6mm studs on my ht. One more thing, would it be a good idea to use an NT speed carb instead of the stock? It wouldn't be hard to fit a manifold to the 99, and my main concern is the throttle on the stock carb. It will be very complex when I have to make an offset manifold and rig up a throttle, but I have a sbp throttle assembly for the NT. but I'm worried about the performance of the NT. The predy carb is decent quality, but the NT isn't so much. The NT is more tunable, and bigger. I guess I will have to figure out the carb situation once I settle on a mount position.

I never heard of those carbs being used on a Preddy. Are you sure that they will work? My Preddy carb throat is a lot bigger than my HT carbs. 66cc vs 99 cc is quite a difference.
Studs? Where. I've built two 99 cc bikes, and didn't use any studs anywhere except the stock ones on intake/ exhaust.
You won't have any tuning probs with the stock Preddy carb like you do with the HT's. They are allready tuned very well from the factory. You may have to enlarge the main jet very slightly if you change from stock intake/ exhaust.

 

[tigmaster]

I have no info on the carb that You've mentioned,but I have a Dellorto carb from an Indian minicycle I'm using the tank from on My build (Schwinn/Predator build ....Tigmaster....) the Dellorto has a motorcycle type throttle connection like the nt,and its bigger than stock too. About the J/S,if You can post pics it'll help alot,I'm sure as a group we'll help out with any ideas. I hope You have Good luck selling the mower...Tigmaster....

 

[young grease monkey]

I broke the rear mount bolts/studs/rods many times. Whatever you want to call them. I wasn't very nice to that engine lol. Ok thanks for clarifying my idea about the carb. It won't be hard at all to make an adapter manifold for the angle I mount the engine. I now have a good idea about my mount and I think I will have to use up a favor from the machinist, I will make my own bearing plate and have it machined for the bearings. That will save me from having to leave room in the frame for a bearing hub! It will be like, well, a cvt without the cv. On another topic, the carb insulator i.d. is smaller than the port, so I port matched the insulator. I attempted to remove the flywheel nut so I could remove the fan and starter cup, but it might need an impact gun! I removed all other covers and stuff, removed the governor and throttle linkages, and it fits much better now. I'm back to the vertical position, the cylinder will be about 70 degrees. Will finish the mount this weekend, still got summer school. It ends next Monday! Then I will start up my foundry as a business.

 

[young grease monkey]

Ok so I did more work on the mount today, and since I don't want the pedals hitting the flywheel and future belt transmission, it will be mounted the way it was designed to be. It will give me good access to the valves and spark plug as well as make more room below the engine so I can make a stronger mount using at least 3 clamp points. Also, I obviously won't have to rotate the carb and that will let me use the governor shaft as a pivot point for the throttle linkages. I've changed my mind like what, 3 times now?!?! Glad I got it figured out now, for real this time!

 

[young grease monkey]

Parts came today! Back wheel with 12g spokes and coaster brake hub from Pirate Cycles, bearing hub for jack shaft, primary drive v belt pulley, and high grade 8mm zinc plated threaded rod for the engine mount. Cast parts will not be made for a while because I have to comply with fire codes and cover all flammable material within 15 feet of the furnace with sheet metal. The frame is getting sand blasted then powder coated gloss black. Where can I find 2.25 inch street tires? I don't want the monster hookworms, but a semi slick or brick pattern would be ok.

 

[young grease monkey]

Pics of my build progress and parts that came today: www.photobucket.com/enginemount99pred

 

[young grease monkey]

www.photobucket.com/enginemount99pred

Hooked up a throttle control, going to buy return springs tomorrow. Also going to buy professional quality foundry sand tomorrow, it will give the castings a smoother surface finish. I'm going to cut out parts of the engine mount plate to reduce weight, and start making the jackshaft plate wooden mold pattern.

 

[Velodrome]

Parts came today! Back wheel with 12g spokes and coaster brake hub from Pirate Cycles, bearing hub for jack shaft, primary drive v belt pulley, and high grade 8mm zinc plated threaded rod for the engine mount. Cast parts will not be made for a while because I have to comply with fire codes and cover all flammable material within 15 feet of the furnace with sheet metal. The frame is getting sand blasted then powder coated gloss black. Where can I find 2.25 inch street tires? I don't want the monster hookworms, but a semi slick or brick pattern would be ok.

What color do you want in tires? I have a pair of these on the Felt Twin. They are FAT at 26x2.35 http://www.amazon.com/Electra-diamond-tire-Vintage-Diamond/dp/B0030IG210 Pic for comparison to a 26x2.125 I'd stick with 26x2.125. These fattys caused me a bunch of problems getting things to line up.

 

[young grease monkey]

I think I will use some knobby tires for a while then switch to heavy duty e-bike tires. Today I fired up the engine for the first time since disassembling for mods. I removed the governor, ported the head, and lapped the valves, and polished the combustion chamber. I did not deck the head, that may come later. I will try to re-cast the mount and make the jackshaft plate this weekend.

 

[young grease monkey]

Fired the engine up, runs great! Needs a bigger main jet. Sanded down the shaft so the pulley fits nicely now. Will work on the plate tomorrow.

 

[young grease monkey]

Got the frame back, check my photobucket album linked in earlier posts. It looks really good, I have to wire wheel the steer tube bearing races cuz they didn't mask them off but I can't complain for $50! I also found out that one of the guys in my engineering class has a small machine shop! I will probably have him deck the head after I finish the bike. Maybe he can help me make a sprocket adapter? Can anybody tell me the distance between the sprocket mount holes for a mm or flyer adapter? Can I buy just a sprocket for either of those adapters?

 

[young grease monkey]

its been a while since I posted my progress, but the mount is done. used steel tubes cut in half and welded flanges to bolt onto the down tube and seat tube. 6 inches of clamp length on both tubes, this is an extremely ridged strong mount while protecting the frame from too much stress. bearing will mount between seat tube and engine, its a tight fit but will look good and clean.

engine has been modded as much as it can be without buying parts. .05 milled off the head, valves polished to reflect heat and resist carbon build up, combustion chamber polished, ports ported and used filler material on the intake port to smooth out the bowl.

fired it up, sounds great its gonna be a tire shredder! right now its geared for 30 mph at 5600rpm I believe, will change that. I might carry another pulley and hex key to change em out whenever I want. the pulleys and belt are very close to the engine, only adds about an inch to the width of the engine. the exhaust will need wrap and guards, its very close to my leg. will be a dual exhaust using the gutted mufflers from 2 stroke kits and chrome plated tubing from an outdoor chair. I will make my own glass pack inserts for the mufflers.

once I have it ridable I need to get suspension forks and hyd disc brake. for now its just rim brakes front coaster rear

will have pics later today hopefully