12-08-2017, 11:07 AM
(This post was last modified: 12-08-2017, 11:08 AM by flowerlandfilms.)
I'd heard a lot of talk about an SRV engine being identical to a Virago, and that they could be swapped interchangeably, but I couldn't find anyone who had actually done it.
So when my 1995 SRV-250 engine seized, I SEIZED the opportunity, purchased a 1998 Virago 250 engine from a wreckers, and swapped it in.. and it works!
It was two weeks of hard slog, especially because I'm learning about motors as I go, and I've never been in an engine before now.
A lot of my SRV bolts and screws were stripped/rusted/frozen, and had to be drilled/coaxed/chiselled out, which didn't do my arms any favours.
But despite claims to the contrary there are some differences and incompatibilities people should be aware of. I hope this list helps if you are in the same predicament as me:
- The Cylinder Heads are NOT the same. Virago heads will fit in the SRV, but they will not be correctly spaced apart for the Carburettor joints for the twin carbs. The virago carb ports are flush with the fins, the SRV ports are recessed into the head, to make more room for the twin joints.
You could use the Virago heads with their own carb, or possibly with a different carb setup, but you must have the SRV heads to fit the SRV carbs. Virago heads could be turned into SRV heads if you took a hacksaw to the fins I think, but I aint that desperate.
- The Cams have different shaped lobes affecting performance, but each head will take each cam with no problems, the recommended valve clearances are the same for both bikes: Intake Valve 0.08 ~ 0.12 - Exhaust valve 0.10 ~ 0.14
- The Cam Sprockets are identical
- The 1995 SRV that I own mounted its drive sprocket with one big central nut, and a washer bent around it to hold it in place. The Virago sprocket has two screws either side which go through a guide plate. The sprockets were incompatible so I had to switch to the Virago sprocket.
You could probably drill two holes in an SRV sprocket to make them work, or if you wanted to you could probably replace the shaft and mount an SRV shaft in its place, but once again that seems like a lot of effort, I can just buy Virago sprockets from now on.
MY SRV chain length was fine and it fits the sprocket no problem, I believe the amount of teeth on the sprocket is the same if stock.
- All the engine covers can be swapped so the Virago engine looks just like the SRV engine. (Of course apart from the ID Number, I went from 4DN-000136 to 3LV-021734![[Image: icon_oops.gif]](http://viragotechforum.com/images/smilies/icon_oops.gif)
) The Virago engine had a plastic chain/sprocket cover, so I was happy to be able to use my steel SRV one.
- The cylinder head covers on the Virago mount from the top, whereas on the SRV, they mount from the side. Each engine has different shaped brackets to achieve this, so you will need SRV brackets to fit SRV head covers. But either bracket will fit on either engine.
- The screw which holds the clutch actuator arm in place, not sure what it's called but it's a specialty screw with a built in copper washer, and a notch cut out of the end, has a slightly different shaped notch for each bike.
I am not sure if this effects compatibility, it might just be a redesign of the part and work for both, but to be safe maybe use your own engines screw.
- There is a thick hose which comes off the back of the engine, I'm not sure where it goes, the Air Filter or something? Anyway it goes out to the right of the Virago engine, out to the left of the SRV engine.
The hose on the SRV will not be long enough to reach it due to the switched sides. You will need a longer hose. I got one at SCA, I think it was for a Holden Statesman.
It's running well, and i've not had any problems with it so far. Virago cam performance definitely has less "Up and Go", I'll see what effect this has on Fuel economy before going back to the SRV cams.
So when my 1995 SRV-250 engine seized, I SEIZED the opportunity, purchased a 1998 Virago 250 engine from a wreckers, and swapped it in.. and it works!
It was two weeks of hard slog, especially because I'm learning about motors as I go, and I've never been in an engine before now.
A lot of my SRV bolts and screws were stripped/rusted/frozen, and had to be drilled/coaxed/chiselled out, which didn't do my arms any favours.
But despite claims to the contrary there are some differences and incompatibilities people should be aware of. I hope this list helps if you are in the same predicament as me:
- The Cylinder Heads are NOT the same. Virago heads will fit in the SRV, but they will not be correctly spaced apart for the Carburettor joints for the twin carbs. The virago carb ports are flush with the fins, the SRV ports are recessed into the head, to make more room for the twin joints.
You could use the Virago heads with their own carb, or possibly with a different carb setup, but you must have the SRV heads to fit the SRV carbs. Virago heads could be turned into SRV heads if you took a hacksaw to the fins I think, but I aint that desperate.
- The Cams have different shaped lobes affecting performance, but each head will take each cam with no problems, the recommended valve clearances are the same for both bikes: Intake Valve 0.08 ~ 0.12 - Exhaust valve 0.10 ~ 0.14
- The Cam Sprockets are identical
- The 1995 SRV that I own mounted its drive sprocket with one big central nut, and a washer bent around it to hold it in place. The Virago sprocket has two screws either side which go through a guide plate. The sprockets were incompatible so I had to switch to the Virago sprocket.
You could probably drill two holes in an SRV sprocket to make them work, or if you wanted to you could probably replace the shaft and mount an SRV shaft in its place, but once again that seems like a lot of effort, I can just buy Virago sprockets from now on.
MY SRV chain length was fine and it fits the sprocket no problem, I believe the amount of teeth on the sprocket is the same if stock.
- All the engine covers can be swapped so the Virago engine looks just like the SRV engine. (Of course apart from the ID Number, I went from 4DN-000136 to 3LV-021734
) The Virago engine had a plastic chain/sprocket cover, so I was happy to be able to use my steel SRV one.- The cylinder head covers on the Virago mount from the top, whereas on the SRV, they mount from the side. Each engine has different shaped brackets to achieve this, so you will need SRV brackets to fit SRV head covers. But either bracket will fit on either engine.
- The screw which holds the clutch actuator arm in place, not sure what it's called but it's a specialty screw with a built in copper washer, and a notch cut out of the end, has a slightly different shaped notch for each bike.
I am not sure if this effects compatibility, it might just be a redesign of the part and work for both, but to be safe maybe use your own engines screw.
- There is a thick hose which comes off the back of the engine, I'm not sure where it goes, the Air Filter or something? Anyway it goes out to the right of the Virago engine, out to the left of the SRV engine.
The hose on the SRV will not be long enough to reach it due to the switched sides. You will need a longer hose. I got one at SCA, I think it was for a Holden Statesman.
It's running well, and i've not had any problems with it so far. Virago cam performance definitely has less "Up and Go", I'll see what effect this has on Fuel economy before going back to the SRV cams.
