Ton up SR250: 100mph, 100kg, 30hp

JadusMotorcycleParts

Over 1,000 Posts
DTT SUPPORTER
Finned engine covers for extra cooling arrived and are installed :D
 

Attachments

  • SR250_EngineInFrame.JPG
    SR250_EngineInFrame.JPG
    402.1 KB · Views: 144
  • SR250_FinnedCamCover.JPG
    SR250_FinnedCamCover.JPG
    345.7 KB · Views: 124
  • SR250_FinnedEngineCovers.JPG
    SR250_FinnedEngineCovers.JPG
    340.1 KB · Views: 104
  • SR250_FinnedValveCovers.JPG
    SR250_FinnedValveCovers.JPG
    492.6 KB · Views: 113

JadusMotorcycleParts

Over 1,000 Posts
DTT SUPPORTER
Can highly recommend SuperSprox! What a sweet service! Will def use this in the future. The sprocket came in even lighter than expected - at 240g-ish. Decent weight savings here, especially unsprung mass. Now got the rear wheel assembled and ready to go in the frame. I tracked down a decent lightweight, low friction but strong chain as well - after reading a lot about different types. I like the all silver look :D too
 

Attachments

  • SR250_RearSprockets1.JPG
    SR250_RearSprockets1.JPG
    332.4 KB · Views: 80
  • SR250_RearSprockets2.JPG
    SR250_RearSprockets2.JPG
    341.7 KB · Views: 84
  • SR250_RearSprockets4.JPG
    SR250_RearSprockets4.JPG
    211.8 KB · Views: 74
  • SR250_RearSprockets3.JPG
    SR250_RearSprockets3.JPG
    346.4 KB · Views: 78
  • SR250_RearSprockets5.JPG
    SR250_RearSprockets5.JPG
    360.3 KB · Views: 72
  • SR250_ChosenChain.JPG
    SR250_ChosenChain.JPG
    447.2 KB · Views: 77
Last edited:

JadusMotorcycleParts

Over 1,000 Posts
DTT SUPPORTER
I was lucky that I had two decent fork stanchions for this bike - many old SR250 forks get terrible corrosion. There were no issues in the 'working' area of these, however there were a few small rust spots that I wanted to address. I had seen this fix method somewhere online and decided to give it a go myself.

So I sanded back the spots with 400 grit sandpaper, cleaned it with acetone, then filled with a really strong gap filling 2 part epoxy. Then waited for it to harden and sanded it back carefully. It looks like it has worked but I am not certain how long it is going to stay put! Perhaps there is another type of two part epoxy that would have been better suited to this. Oh well, this area of the forks will be covered anyway by the custom headlight brackets - as well as being sealed and water proofed (held in place with orings).
 

Attachments

  • RustedForks1.JPG
    RustedForks1.JPG
    390.8 KB · Views: 75
  • RustedForks2.JPG
    RustedForks2.JPG
    246.1 KB · Views: 61
  • RustedForks3.JPG
    RustedForks3.JPG
    251.1 KB · Views: 71
  • RustedForks4.JPG
    RustedForks4.JPG
    243 KB · Views: 73
  • RustedForks5.JPG
    RustedForks5.JPG
    259.5 KB · Views: 80

ridesolo

“Kto ne riskuet, ne pyot champanskoye.”
DTT SUPPORTER
DTT BOTM WINNER
I've never seen that approach tried before. What the heck, looks like it's worth a try, why not? Good luck w/ it.
 

JadusMotorcycleParts

Over 1,000 Posts
DTT SUPPORTER
I measured up the lengths required for the new custom cables I will be ordering - to suit both the lower clip on position and the new brake set up. I have created some drawings for these cables to be able to send to Venhill who make them: https://www.venhill.co.uk/

I have attached the drawings here for others to use (PDFs and JPEGs). Just make sure to measure your own lengths and modify the drawing to reflect that - it is just the 'HOUSING LENGTH' dimension that will need to be change, all other dimensions work with the stock carb, brakes and clutch.
 

Attachments

  • SR250_BrakeCable.pdf
    3.5 MB · Views: 32
  • SR250_ClutchCable.pdf
    4.3 MB · Views: 24
  • SR250_ThrottleCable.pdf
    5.7 MB · Views: 24
  • SR250_BrakeCable.jpg
    SR250_BrakeCable.jpg
    939.1 KB · Views: 54
  • SR250_ClutchCable.jpg
    SR250_ClutchCable.jpg
    910.4 KB · Views: 56
  • SR250_ThrottleCable.jpg
    SR250_ThrottleCable.jpg
    932.6 KB · Views: 81

JadusMotorcycleParts

Over 1,000 Posts
DTT SUPPORTER
I wasn't satisfied with the slow pace of the project and felt pressure to get it done for the coming riding season... that is already upon us! So I took a few days off work in March to be able to leapfrog a few steps and get back on track. Now I have a rolling chassis and have started working on some of the other details - guards, linkages, electronics etc. I will share a few of those updates in subsequent posts.

This part of the project is really fun - so much planning and thought has gone in to each part, it is nice to finally see it all coming together :D
 

Attachments

  • SR250_Progress1.JPG
    SR250_Progress1.JPG
    628.7 KB · Views: 73
  • SR250_Progress2.JPG
    SR250_Progress2.JPG
    653.2 KB · Views: 73
  • SR250_RearSetLinkage.JPG
    SR250_RearSetLinkage.JPG
    368.2 KB · Views: 69

JadusMotorcycleParts

Over 1,000 Posts
DTT SUPPORTER
An update on some of the electrics... By removing the electric starter I could also remove the starter relay and safety relay (cuts power to the starter relay in the case that the bike is in gear or clutch not pulled in) and the associated wiring that goes with those components. It will be nice to have a little simpler wiring harness. I was also able to fix the starter button in position and label it 'NOPE' on the bead blasted stock switch blocks :D I really like these small hand-made touches here and there - so the bike does not look too 'machine'.

I have also shortened the switch block cables (too much wiring in the headlight otherwise) and the speedo cables.

I am glad I ordered two sets of the custom headlight bolts for the mini blinkers because the second set will get used in the rear - picture of that coming soon!
 

Attachments

  • SR250_WireHarnessStock.JPG
    SR250_WireHarnessStock.JPG
    380.6 KB · Views: 50
  • SR250_WireHarnessSimplified.JPG
    SR250_WireHarnessSimplified.JPG
    372.3 KB · Views: 42
  • SR250_BlastedSwitches.JPG
    SR250_BlastedSwitches.JPG
    486.4 KB · Views: 43
  • SR250_ShortenedSwitchCables.JPG
    SR250_ShortenedSwitchCables.JPG
    464 KB · Views: 45
  • SR250_BlastedControls.JPG
    SR250_BlastedControls.JPG
    153.8 KB · Views: 48
  • SR250_ControlButtons.JPG
    SR250_ControlButtons.JPG
    214.6 KB · Views: 50
  • SR250_HeadlightBolts.JPG
    SR250_HeadlightBolts.JPG
    445.9 KB · Views: 49
  • SR250_MiniBlinkers.JPG
    SR250_MiniBlinkers.JPG
    184.7 KB · Views: 56

JadusMotorcycleParts

Over 1,000 Posts
DTT SUPPORTER
A few more parts taking shape. A trimmed guard - much lighter than stock :D Grommeted holes in the guards for mounting - vibration damping. And a trimmed and modified speedo bracket - for the new unit.
 

Attachments

  • SR250_StockFrontGuard.JPG
    SR250_StockFrontGuard.JPG
    349.1 KB · Views: 41
  • SR250_JadusGuard.JPG
    SR250_JadusGuard.JPG
    271.2 KB · Views: 42
  • SR250_TrimmingJadusGuard.JPG
    SR250_TrimmingJadusGuard.JPG
    332.4 KB · Views: 42
  • SR250_AlloyGuard.JPG
    SR250_AlloyGuard.JPG
    322.1 KB · Views: 41
  • SR250_TrimmedJadusGuard1.JPG
    SR250_TrimmedJadusGuard1.JPG
    281.2 KB · Views: 42
  • SR250_AlloyRearGuard.JPG
    SR250_AlloyRearGuard.JPG
    162.1 KB · Views: 45
  • SR250_AluminiumRearGuard.JPG
    SR250_AluminiumRearGuard.JPG
    165.8 KB · Views: 41
  • GuardMountRubbers.JPG
    GuardMountRubbers.JPG
    157.7 KB · Views: 41
  • SR250_Speedobracketmod.JPG
    SR250_Speedobracketmod.JPG
    161.6 KB · Views: 42
  • SR250_Speedobracketmod1.JPG
    SR250_Speedobracketmod1.JPG
    188.2 KB · Views: 44

JadusMotorcycleParts

Over 1,000 Posts
DTT SUPPORTER
And some more parts taking shape... A trimmed battery tray - I designed the tray so that it could be used with both an 8 cell and 4 cell lithium battery but I had never actually tried it with the 4 cell - always wanting the extra juice for the starter. But now with kickstart only I could try it and it works great. I could also remove the tab for the starter relay - not needing that any more either. I also decided to use some XT60 connectors for the battery - so I can easily disconnect it in case of any parasitic drains that are difficult to find (lithium batteries, as you know, die if drained below a certain voltage - ask anyone how they know hehe). And also to be able to easily connect a charger while the battery is still in place - wiring up an adaptor with a plug to the charger. Together with this I made a small power harness that connects back into the main wire harness. This one has two grounds to be sure - one running to an engine cover bolt, the other running up to the main frame ground by the ignition coil.

And finally, I will be using an old bellmouth prototype on this bikes intake - the one that I had made to fit different length tubes to be able to dyno test the length of our performance intake kit. However, with the hopes of having power at peak rpm instead of a nice torque spread in the middle, this intake will be shorter - so I calculated where the 3rd harmonic would be at peak power/rpm and will trim it to that - at 90mm. It seemed a shame not to have this cool piece of machining in use, so now it will get a deserving installment.

I am chipping away at the wire harness and will give a decent update with some full shot photos soon! :D
 

Attachments

  • SR250_JadusBatteryTray.JPG
    SR250_JadusBatteryTray.JPG
    133.6 KB · Views: 23
  • SR250_TrimmedJadusBatteryTray.JPG
    SR250_TrimmedJadusBatteryTray.JPG
    228.7 KB · Views: 24
  • SR250_LightWeightBattery.JPG
    SR250_LightWeightBattery.JPG
    181.7 KB · Views: 25
  • SR250_4CellBatteryTray.JPG
    SR250_4CellBatteryTray.JPG
    232.3 KB · Views: 26
  • XT60_Connectors.JPG
    XT60_Connectors.JPG
    347.3 KB · Views: 26
  • SR250_LithiumBattery.JPG
    SR250_LithiumBattery.JPG
    495.5 KB · Views: 26
  • SR250_CustomPowerCables.JPG
    SR250_CustomPowerCables.JPG
    471.3 KB · Views: 26
  • SR250_CustomBellmouth.JPG
    SR250_CustomBellmouth.JPG
    209.5 KB · Views: 29
  • SR250_TunedIntake.JPG
    SR250_TunedIntake.JPG
    291.4 KB · Views: 27
  • SR250_Speedobracketmod2.JPG
    SR250_Speedobracketmod2.JPG
    118.8 KB · Views: 32

JadusMotorcycleParts

Over 1,000 Posts
DTT SUPPORTER
Finally, a decent update...
  • Carb restored (cleaned, re-jetted, butterfly valve mod, air/fuel screw upgrade)
  • Wire harness 95% sorted - battery connectors installed, ignition 'switch' (replaces keyed ignition) installed (see above carb), all lights installed and operating - see the solutions for mounting the blinkers, pretty happy about that, speedo and switches installed and wired up, ignition coil and spark lead and plug installed, battery tray and electrics tray installed - with automotive fuse holder and relocated Reg/Rec
  • Steering stop bolts installed - to reduce rotational travel of the clipons so they don't foul the tank
  • Drilled fork brace installed with trimmed guard with brushed look and installed with isolation grommets (vibes)
  • Front brake bracket installed with custom short brake cable and cable guide from a Yamaha motocross bike
  • Speed sensor bracket made and sensor (Hall) installed - picks up the sprocket bolts on the wheel (this is dialled in once running)
  • Clutch and throttle cables installed and adjusted (shorter than stock)
  • Rear sets sorted - now with bracket for brake light switch
The last big jobs are to finish off the wiring and then sort the exhaust. I have used some exhaust calculators to calculate the preferred header length and have bought some adaptors so I can weld it all together with the Jadus 20 bend adaptor and install a vacuum pick up tube for the PCV valve/pump (from XS650).

If all goes well, first start will be by the end of the month (June)! :D
 

Attachments

  • SR250_WiringDone.JPG
    SR250_WiringDone.JPG
    654.6 KB · Views: 12
  • SR250_CafeRacer.JPG
    SR250_CafeRacer.JPG
    642.7 KB · Views: 12
  • SR250_RestoredCarb.JPG
    SR250_RestoredCarb.JPG
    477.6 KB · Views: 9
  • SR250_SteeringStops.JPG
    SR250_SteeringStops.JPG
    371.9 KB · Views: 9
  • SR250_ForkBraceGuard.JPG
    SR250_ForkBraceGuard.JPG
    515.1 KB · Views: 9
  • SR250_FrontBrake.JPG
    SR250_FrontBrake.JPG
    565.6 KB · Views: 10
  • SR250_HallSensor.JPG
    SR250_HallSensor.JPG
    479.4 KB · Views: 11
  • SR250_Rearsets.JPG
    SR250_Rearsets.JPG
    588.4 KB · Views: 10
  • SR250_RearBlinkers.JPG
    SR250_RearBlinkers.JPG
    484.8 KB · Views: 9
  • SR250_Rearsets_BrakeSwitch.JPG
    SR250_Rearsets_BrakeSwitch.JPG
    434.8 KB · Views: 14

JadusMotorcycleParts

Over 1,000 Posts
DTT SUPPORTER
What’s this butterfly valve mod you did?
It is old hot rodding trick that increases carb throat area by cutting off one side of the butterfly valve holder - so it is a blade rather than a fork. In this case, area increases by around 10%. Who knows how much it will help, but thought why not try it! Hoping the engine will want to consume that much more air at least :)
 

Attachments

  • ButterflyShaftMod.jpg
    ButterflyShaftMod.jpg
    768.2 KB · Views: 12

DTT Bike Of The Month Gallery

DTT Light or Dark

www.jadusmotorcycleparts.com
shop.themotoworks.com
www.cognitomoto.com
https://www.townmoto.com
www.speedmotoco.com
www.lostapostle.ca/
www.sparckmoto.com
Top Bottom