karlok
L plate rider.
Posts: 15
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Post by karlok on Jan 17, 2024 8:55:55 GMT 1
Hi everybody, Starting a thread to share my new project, it is actually one of my dream bikes but as always I need to make it a bit more complicated with modification in pursuit for a little more engine power. I'm not a racer or a pro driver but like to feel some 2 stroke ponies underneath me. Work will be slow with big gaps due to my job which makes me spend most of my time abroad.
The story: Bike was bought on Christmas 2019 as a present from me to me  for around 1100e in non running condition. ~35k kilometeres in original condition. It was parked for more than 6 years because the fuel tank was leaking (after an unsuccessful repair) and as a result the crank bearings corroded a bit. Photo of it when brought home.
Fuel tank concerns:
Somebody was riding pretty hard before being parked (bike was bought very close from Grobnik racetrack in Croatia) After many sleepless (and penniless  ) months, in between other projects and stuff going on the RD time has come. Keeping the original LC cases and complete look was an idea, I have decided to go with Athena big bore kit, as we all know they don't fit the LC cases. Regardless, me being stubborn is a fact and parts were ordered so there is no going back.  Engine was disassembled and everything inside looks really good, pistons are original, and original size. Not much wear and crank bearings were no worn, just pitted slightly. Ordered complete gasket set, seals and a new crankshaft from Yamaha, since LC one was discontinued, Banshee crank was ordered and will be made to fit. Testing for crank fitting, clearance is tight but it spins freely except gearbox side crank bearing half moon is offset, shown on the photo. Instead of thinning the crank webs where the bearing sits, bearing will be flipped and a complete new slot will be machined, surprised myself when one of the pullers fitted like a glove on the crank bearing groove and made this task an easy job. Crank testfit: The groove issue: The Crime: Adding missing material, case material is surprisingly porous and had many impurities inside which made welding hard.
Looks enough
Welding distorted the top portion of cases significantly, even more than expected and if doing another engine, some sort of jig will be used to reduce distortion.
Middle section was pushed down, and gaps appeared at the front sealing surfaces on the cases, show on photos. It was a big job to straighten surfaces, a lot of adjusting to reduce amount of material that needs to be removed. In the end all surfaces were rechecked (gearbox side and ignition side to ensure proper sealing).
Getting exciting: Since we removed material between cases, now the bearing seats (and seals seats) were out of round (and too tight) on the upper half of the case. We had to line bore all the bearing seats, and ignition plate recess, both the gearbox shafts and crankshaft. We used bottom half as a reference and machined only the top crankcase half. This was harder then expected as we did not have a tool that will go deep enough in one go to bore the crank and one of the gearbox seats. So we used the tools to make more tools so we can use new tools in combination with old tools so it was in reality toolception. Fun stuff because everybody at the machine shop looked us like we were out of our mind.  At this time we also did the new groove for the crank bearing half moon but I have no pictures of that.
All this work took around 30hrs to complete and it would not be done without my awesome friend who made sacrifices to his sleep schedule in order to do this for me, so once more I owe him. Cylinder spacer also needs to be made, but in order to get the exact thickness for the spacer I will need to assemble the engine first, so we will leave this for the further date as I need to machine the welded area to make it more presentable (the visible area under cylinders mostly). Next, I have removed the paint from the tank (yes I'm wearing the invisible safety glasses and dust mask, balkan version  ) Its badly corroded at the bottom and previous repair was not done properly so still have to make a decision on to repair it or replace. Unfortunately this is all that was managed over the holidays, now another work rotation.
Stuff to decide while away:
1.Installing pneumatic powervalves (rave valves from rotax 787) or not. Will require welding on new cylinders, and then some cnc machining. Possible bore distortion due to welding and penetrating in to cooling passages when machining 2.Programmable cdi (Zeeltronic) or leave it stock?
3.Oversize carbs, I'm looking more at a moderate upgrade, possible 30mm dellortos or similar. I would like to keep the airbox, perhaps modify it but to keep the noise level down. I dont like too much intake noise. 4.Reed valves, stock with new reeds and ported or something different altogether?
5.350 oil pump + modding (already have one) or premix 6.Front calipers, Master and discs, would like to preserve OEM look as much as possible, perhaps just add 350 disc (250 came with one only) and fj1200 4 pot calipers with braided lines, I think they are a bolt on fit. All inputs are welcome.  |
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Post by shaunthe2nd on Jan 17, 2024 9:23:30 GMT 1
Great intro to your bike - you got a bargain at 1000 Euro, as it looks complete. We are lucky to get frame and engine cases for this money in UK!
Some great work there, I admire your skills.
Good luck with the build, keep us posted and look forward to reading more.
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Post by midlifecrisisrd on Jan 17, 2024 9:34:23 GMT 1
Wow 🤯
That's a lot of machining work, admire the commitment 👍
A few opinions on your questions
Programmable ignition? - definitly
Airbox? - think it will have to go as restrictive
Carbs? - yes upgrade. Keihin PWK 28's will go on with standard airbox I think
Front end? - if wanting to keep the standard look then at least use 83/84 ypvs yokes/forks. Direct replacement but 35mm instead of 32mm
Steve
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Post by billbott on Jan 17, 2024 10:05:20 GMT 1
Great thread, looking forward to more updates. I too work in engineering and all I can say is your boss is far better than mine – I struggle to get a washer made…………!
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Post by charles13 on Jan 17, 2024 13:10:13 GMT 1
Hi everybody, Starting a thread to share my new project, it is actually one of my dream bikes but as always I need to make it a bit more complicated with modification in pursuit for a little more engine power. I'm not a racer or a pro driver but like to feel some 2 stroke ponies underneath me. Work will be slow with big gaps due to my job which makes me spend most of my time abroad.
The story: Bike was bought on Christmas 2019 as a present from me to me for around 1100e in non running condition. ~35k kilometeres in original condition. It was parked for more than 6 years because the fuel tank was leaking (after an unsuccessful repair) and as a result the crank bearings corroded a bit. Photo of it when brought home.
Fuel tank concerns:
Somebody was riding pretty hard before being parked (bike was bought very close from Grobnik racetrack in Croatia) After many sleepless (and penniless ) months, in between other projects and stuff going on the RD time has come. Keeping the original LC cases and complete look was an idea, I have decided to go with Athena big bore kit, as we all know they don't fit the LC cases. Regardless, me being stubborn is a fact and parts were ordered so there is no going back. Engine was disassembled and everything inside looks really good, pistons are original, and original size. Not much wear and crank bearings were no worn, just pitted slightly. Ordered complete gasket set, seals and a new crankshaft from Yamaha, since LC one was discontinued, Banshee crank was ordered and will be made to fit. Testing for crank fitting, clearance is tight but it spins freely except gearbox side crank bearing half moon is offset, shown on the photo. Instead of thinning the crank webs where the bearing sits, bearing will be flipped and a complete new slot will be machined, surprised myself when one of the pullers fitted like a glove on the crank bearing groove and made this task an easy job. Crank testfit: The groove issue: The Crime: Adding missing material, case material is surprisingly porous and had many impurities inside which made welding hard.
Looks enough
Welding distorted the top portion of cases significantly, even more than expected and if doing another engine, some sort of jig will be used to reduce distortion.
Middle section was pushed down, and gaps appeared at the front sealing surfaces on the cases, show on photos. It was a big job to straighten surfaces, a lot of adjusting to reduce amount of material that needs to be removed. In the end all surfaces were rechecked (gearbox side and ignition side to ensure proper sealing).
Getting exciting: Since we removed material between cases, now the bearing seats (and seals seats) were out of round (and too tight) on the upper half of the case. We had to line bore all the bearing seats, and ignition plate recess, both the gearbox shafts and crankshaft. We used bottom half as a reference and machined only the top crankcase half. This was harder then expected as we did not have a tool that will go deep enough in one go to bore the crank and one of the gearbox seats. So we used the tools to make more tools so we can use new tools in combination with old tools so it was in reality toolception. Fun stuff because everybody at the machine shop looked us like we were out of our mind. At this time we also did the new groove for the crank bearing half moon but I have no pictures of that.
All this work took around 30hrs to complete and it would not be done without my awesome friend who made sacrifices to his sleep schedule in order to do this for me, so once more I owe him. Cylinder spacer also needs to be made, but in order to get the exact thickness for the spacer I will need to assemble the engine first, so we will leave this for the further date as I need to machine the welded area to make it more presentable (the visible area under cylinders mostly). Next, I have removed the paint from the tank (yes I'm wearing the invisible safety glasses and dust mask, balkan version ) Its badly corroded at the bottom and previous repair was not done properly so still have to make a decision on to repair it or replace. Unfortunately this is all that was managed over the holidays, now another work rotation.
Stuff to decide while away:
1.Installing pneumatic powervalves (rave valves from rotax 787) or not. Will require welding on new cylinders, and then some cnc machining. Possible bore distortion due to welding and penetrating in to cooling passages when machining 2.Programmable cdi (Zeeltronic) or leave it stock?
3.Oversize carbs, I'm looking more at a moderate upgrade, possible 30mm dellortos or similar. I would like to keep the airbox, perhaps modify it but to keep the noise level down. I dont like too much intake noise. 4.Reed valves, stock with new reeds and ported or something different altogether?
5.350 oil pump + modding (already have one) or premix 6.Front calipers, Master and discs, would like to preserve OEM look as much as possible, perhaps just add 350 disc (250 came with one only) and fj1200 4 pot calipers with braided lines, I think they are a bolt on fit. All inputs are welcome. Was all that machine work just to get the Athena cylinders on the 250lc cases? You also mentioned a spacer will this be 421cc? |
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Post by JonW on Jan 17, 2024 13:20:58 GMT 1
Wow, a lot of work there, I also admire your efforts. Very interesting build |
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karlok
L plate rider.
Posts: 15
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Post by karlok on Jan 17, 2024 18:49:23 GMT 1
Was all that machine work just to get the Athena cylinders on the 250lc cases? You also mentioned a spacer will this be 421cc? That is a big quote
The dillema was between just using an adapter plate to fit cylinders, which I am not a fan of as it needs to be around 8mm +/- so I was scared of threads stripping, adapter plate flexing that may cause leaks, was trying to avoid steel or stainless plate. The welder friend assured me that there wont be that much distortion from welding so as this will give it an more "oem look" when finished I opted for this. All the machine work except the cylinder base plate was needed to be done because of distortion.
After welding there was no more going back. With all the experience now I would have probably opted to buy a stroker crank and try to get away with a thicker adapter plate, the challenge with plate is bolt spacing is very close to original studs but not matching.
The 8mm adaptor plate is required because banshee (athena) pistons have higher compression height for 8mm compared to LC engine (connecting rod is the same length).
This way, in a future rebuild, to stroke the engine only the crank (banshee) and thicker plate would be required. Using banshee top end also gives more options further down the line in sense of more tuning if needed and they are more common.
Life is a learning curve. |
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Post by arrow on Jan 17, 2024 19:36:16 GMT 1
Wow, this is what I'd call a full on project! Lots of engineering work going on there.
I can supply the uprated pump for the 421cc engine. Using the pump you have for modification.
It's a well proven unit.
This is only necessary if you intend to use the standard primary gears. After market primary gears are out there and a combination of bigger crank gear and various wormshaft drive gears are available, and it's possible to then run the standard pump. After market primary gears aren't cheap though....
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karlok
L plate rider.
Posts: 15
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Post by karlok on Jan 17, 2024 20:04:29 GMT 1
Wow 🤯 That's a lot of machining work, admire the commitment 👍 A few opinions on your questions Programmable ignition? - definitly Airbox? - think it will have to go as restrictive Carbs? - yes upgrade. Keihin PWK 28's will go on with standard airbox I think Front end? - if wanting to keep the standard look then at least use 83/84 ypvs yokes/forks. Direct replacement but 35mm instead of 32mm Steve Is there any alternative airbox avaliable? Great thread, looking forward to more updates. I too work in engineering and all I can say is your boss is far better than mine – I struggle to get a washer made…………! Its friends boss, we did it all after hours, stayed until 5am few nights, we are not that smart Wow, this is what I'd call a full on project! Lots of engineering work going on there. I can supply the uprated pump for the 421cc engine. Using the pump you have for modification. It's a well proven unit. This is only necessary if you intend to use the standard primary gears. After market primary gears are out there and a combination of bigger crank gear and various wormshaft drive gears are available, and it's possible to then run the standard pump. After market primary gears aren't cheap though.... Are primary gears off something OEM or only aftermarket product? I could probably get the gears made, it would take some time but not impossible. |
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Post by arrow on Jan 17, 2024 20:26:54 GMT 1
Wow 🤯 That's a lot of machining work, admire the commitment 👍 A few opinions on your questions Programmable ignition? - definitly Airbox? - think it will have to go as restrictive Carbs? - yes upgrade. Keihin PWK 28's will go on with standard airbox I think Front end? - if wanting to keep the standard look then at least use 83/84 ypvs yokes/forks. Direct replacement but 35mm instead of 32mm Steve Is there any alternative airbox avaliable? Great thread, looking forward to more updates. I too work in engineering and all I can say is your boss is far better than mine – I struggle to get a washer made…………! Its friends boss, we did it all after hours, stayed until 5am few nights, we are not that smart Wow, this is what I'd call a full on project! Lots of engineering work going on there. I can supply the uprated pump for the 421cc engine. Using the pump you have for modification. It's a well proven unit. This is only necessary if you intend to use the standard primary gears. After market primary gears are out there and a combination of bigger crank gear and various wormshaft drive gears are available, and it's possible to then run the standard pump. After market primary gears aren't cheap though.... Are primary gears off something OEM or only aftermarket product? I could probably get the gears made, it would take some time but not impossible. As far as I am aware, after market only. |
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Post by midlifecrisisrd on Jan 17, 2024 20:39:12 GMT 1
No other airbox fits I'm afraid
If using the pwk28's you can try a modified airbox
Definitely take the rubber snorkel out the top, even run with no lid at all
Steve
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karlok
L plate rider.
Posts: 15
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Post by karlok on Jan 17, 2024 21:01:05 GMT 1
No other airbox fits I'm afraid If using the pwk28's you can try a modified airbox Definitely take the rubber snorkel out the top, even run with no lid at all Steve
I will have to check if there is any room to improve this, maybe even 3d printing if required, but it seems tight from the photos I can find online...
Are original carbs not 28mm also or are they 26mm?
Any reason to use pwk specifically?
I have had good experience with round slide dellortos (they have small diameter on the airbox side so easy to fit) on Dt125 with big bore 221cc kit, link to carb: |
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Post by midlifecrisisrd on Jan 17, 2024 21:05:21 GMT 1
Original carbs are 26mm
The PWK's are a common upgrade and fit in the standard rubbers
They give a midrange boost
Steve
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Post by tony2stroke on Jan 18, 2024 17:22:04 GMT 1
Awesome stuff, I love your aptitude, looking forward to seeing more  |
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Post by lcmarky on Jan 18, 2024 17:34:00 GMT 1
Welcome and this looks an interesting project. I like the attitude that nothing is ruled out!! Some good machining skills on show - keep it coming.
I would suggest you go the uprated oil pump with Arrow as after all this work & money you really do want it lubricated properly and pre-mix is too big a risk for a road bike.
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karlok
L plate rider.
Posts: 15
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Post by karlok on Jan 31, 2024 8:32:21 GMT 1
Just got info that a package addressed to my name has arrived to my home country . With photos included it is good news, the exhaust side almost sorted (it will require different flanges due to athena cylinders).
They are DN performance exhausts, mainly aimed for midrange power so rest of the build will follow this.
I'm also thinking on welding egt adapters to the exhaust flanges, or is there an alternative approach to this?
Due to recommendations, I will order Zeeltronic soon, just have to contact Borut does he offer an on/off output for the PV-s in case I decide to use solenoid operated PVs (like rotax122, in case the pneumatic ones will not be adequate)
Other stuff that I need to research more is:
1.Compression ratio, volume with athena kit, supposedly it is 13cc, should be higher, something like 16.5cc?
2.With athena cylinders what port timing should I try to achieve?
3.For the intake, I am thinking boyeseen reeds with ported cages. Is porting these even a thing? 4.Reed spacer is bigger better on rd-s?
I will upgrade carbs in the future, but first I want to see what can I get with stock carbs and modified airbox. It will be dynoed as the butt dyno can be wrong.
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Post by urbantangleweed on Feb 1, 2024 7:24:28 GMT 1
What a fabulous project. Just a thought, but Norbo sells brand new reproduction fuel tanks which are very good if it turns out the one you have needs too much work.
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for around 1100e in non running condition. ~35k kilometeres in original condition. It was parked for more than 6 years because the fuel tank was leaking (after an unsuccessful repair) and as a result the crank bearings corroded a bit.
) months, in between other projects and stuff going on the RD time has come. Keeping the original LC cases and complete look was an idea, I have decided to go with Athena big bore kit, as we all know they don't fit the LC cases. Regardless, me being stubborn is a fact and parts were ordered so there is no going back. 
) Its badly corroded at the bottom and previous repair was not done properly so still have to make a decision on to repair it or replace.
